java.lang.Object
- org.tentackle.sql.backends.AbstractBackend

All Implemented Interfaces:

Backend

Direct Known Subclasses:

AbstractSql92Backend
```
public abstract class AbstractBackend
extends Object
implements Backend
```
Abstract parent class for backends.

Author:

harald

Field Summary

Fields
Modifier and Type	Field	Description
`protected static String`	`TYPE_BIGINT`
`protected static String`	`TYPE_BIT`
`protected static String`	`TYPE_BLOB`
`protected static String`	`TYPE_BOOL`
`protected static String`	`TYPE_BOOLEAN`
`protected static String`	`TYPE_BYTE`
`protected static String`	`TYPE_BYTEA`
`protected static String`	`TYPE_CHAR_1`
`protected static String`	`TYPE_CLOB`
`protected static String`	`TYPE_DATE`
`protected static String`	`TYPE_DATETIME`
`protected static String`	`TYPE_DATETIME_YEAR_TO_SECOND`
`protected static String`	`TYPE_DECIMAL`
`protected static String`	`TYPE_DECIMAL_19`
`protected static String`	`TYPE_DOUBLE`
`protected static String`	`TYPE_FLOAT`
`protected static String`	`TYPE_FLOAT4`
`protected static String`	`TYPE_FLOAT8`
`protected static String`	`TYPE_INT`
`protected static String`	`TYPE_INT2`
`protected static String`	`TYPE_INT4`
`protected static String`	`TYPE_INT8`
`protected static String`	`TYPE_INTEGER`
`protected static String`	`TYPE_NCHAR_1`
`protected static String`	`TYPE_NUMBER`
`protected static String`	`TYPE_NUMBER_1`
`protected static String`	`TYPE_NUMBER_10`
`protected static String`	`TYPE_NUMBER_19`
`protected static String`	`TYPE_NUMBER_5`
`protected static String`	`TYPE_NVARCHAR`
`protected static String`	`TYPE_NVARCHAR_MAX`
`protected static String`	`TYPE_REAL`
`protected static String`	`TYPE_SMALLFLOAT`
`protected static String`	`TYPE_SMALLINT`
`protected static String`	`TYPE_TEXT`
`protected static String`	`TYPE_TIME`
`protected static String`	`TYPE_TIMESTAMP`
`protected static String`	`TYPE_TINYINT`
`protected static String`	`TYPE_VARBINARY_MAX`
`protected static String`	`TYPE_VARCHAR`

Fields inherited from interface org.tentackle.sql.Backend
SQL_ALLSTAR, SQL_ALTER_COLUMN, SQL_ALTER_INDEX, SQL_ALTER_TABLE, SQL_AND, SQL_ANDNOT, SQL_ARRAY_ALL, SQL_ARRAY_ALL_PAR, SQL_ARRAY_ANY, SQL_ARRAY_ANY_PAR, SQL_ARRAY_IN, SQL_ARRAY_IN_PAR, SQL_ARRAY_NOT_IN, SQL_ARRAY_NOT_IN_PAR, SQL_ARRAY_PAR, SQL_COMMA, SQL_COMMA_PAR, SQL_DELETE, SQL_EQUAL, SQL_EQUAL_PAR, SQL_EQUAL_PAR_COMMA, SQL_EQUAL_ZERO, SQL_EXISTS, SQL_FROM, SQL_GREATER, SQL_GREATER_PAR, SQL_GREATEROREQUAL, SQL_GREATEROREQUAL_PAR, SQL_GROUPBY, SQL_IF_EXISTS, SQL_INSERT_INTO, SQL_INSERT_VALUES, SQL_ISNOTNULL, SQL_ISNULL, SQL_LEFT_PARENTHESIS, SQL_LESS, SQL_LESS_PAR, SQL_LESSOREQUAL, SQL_LESSOREQUAL_PAR, SQL_LIKE, SQL_LIKE_PAR, SQL_MAX, SQL_MIN, SQL_NOT, SQL_NOTEQUAL, SQL_NOTEQUAL_PAR, SQL_NOTEQUAL_ZERO, SQL_NOTLIKE, SQL_NOTLIKE_PAR, SQL_OR, SQL_ORDERBY, SQL_ORNOT, SQL_PAR, SQL_PAR_COMMA, SQL_PLUS_ONE, SQL_RIGHT_PARENTHESIS, SQL_SELECT, SQL_SELECT_ALL_FROM, SQL_SET, SQL_SORTASC, SQL_SORTDESC, SQL_UPDATE, SQL_WHERE, SQL_WHEREALL, SQL_WHEREAND, SQL_WHERENOTHING, SQL_WHEREOR

Constructor Summary

Constructors
Constructor Description

AbstractBackend()

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`boolean`	`allowsExpressionsReferringToTablesBeingUpdated()`	Determines whether backend allows expressions referring to tables being updated.
`void`	`assertValidName(SqlNameType nameType, String name)`	Asserts that given string is a valid name and usage.
`String`	`buildSelectSql(String sql, boolean writeLock, int limit, int offset)`	Creates a select statement string from an inner sql string.
`String`	`columnTypeNullDefaultToString(String columnName, SqlType sqlType, int size, int scale, boolean nullable, Object defaultValue)`	Converts an sqltype, size, scale, nullable and default value to a database type declaration.
`String`	`columnTypeToString(SqlType sqlType, int size, int scale)`	Converts an sqltype, size and scale to a database type declaration.
`ColumnMetaData`	`createColumnMetaData(TableMetaData tableMetaData)`	Creates a column meta data instance.
`Connection`	`createConnection(String url, String username, char[] password)`	Creates a jdbc connection.
`IndexColumnMetaData`	`createIndexColumnMetaData(IndexMetaData indexMetaData)`	Creates an index column meta data instance.
`IndexMetaData`	`createIndexMetaData(TableMetaData tableMetaData)`	Creates an index meta data instance.
`protected String`	`createPassword(char[] password)`	Creates a password string from a password char array. Unfortunately, `DriverManager.getConnection(String, String, String)` requires the password as a string.
`TableMetaData`	`createTableMetaData(ModelMetaData modelMetaData, String tableName)`	Creates a meta data instance.
`protected String`	`extractWhereClause(String sql, int whereOffset)`	Extracts the where clause from a given sql.
`String`	`getCoalesceKeyword()`	Gets the keyword for the COALESCE function.
`String`	`getDefaultSchema()`	Gets the default schema name. Some backends store the objects in a default schema, if no explicit schema is given.
`int`	`getDefaultSize(SqlType sqlType)`	Gets the default size if no size given in model.
`String`	`getEmptyString()`	Gets the empty string.
`int`	`getMaxScale(SqlType sqlType, int size)`	Returns the maximum scale for a given SQL-type and size.
`int`	`getMaxSize(SqlType sqlType)`	Returns the maximum size for a given SQL-type.
`DatabaseMetaData[]`	`getMetaData(BackendInfo backendInfo)`	Gets the metadata from the backend.
`MigrationStrategy[]`	`getMigrationStrategy(ColumnMetaData column, String columnName, String comment, SqlType sqlType, int size, int scale, boolean nullable, Object defaultValue)`	Determines the best migration strategy.
`ModelMetaData`	`getModelMetaData(DatabaseMetaData[] metaData, String[] schemas, String... tableNames)`	Retrieves the metadata.
`List<DatabaseMetaDataTableHeader>`	`getTableHeaders(DatabaseMetaData metaData)`	Gets all table headers for a given metadata.
`TableMetaData`	`getTableMetaData(ModelMetaData modelMetaData, String tableName)`	Gets the table meta data for a given table name.
`boolean`	`isArrayOperatorSupported(String operator)`	Returns whether the backend supports given array operator.
`boolean`	`isClobSupported()`	Returns whether the backend support CLOB types. If not, it will be emulated as VARCHAR with the maximum possible size.
`boolean`	`isCommunicationLinkException(SQLException ex)`	Determines whether exception is a communication error.
`boolean`	`isConstraintException(SQLException ex)`	Determines whether exception is a constraint violation.
`boolean`	`isDefaultEqual(ColumnMetaData column, SqlType sqlType, Object defaultValue)`	Checks whether the column's default corresponds to the model's default value.
`boolean`	`isDropIfExistsEnabled()`	Returns whether backend should add IF EXISTS for generated DROPs.
`protected boolean`	`isDropIfExistsSupported()`	Adds "IF EXISTS" to drop clauses, if supported by the backend. Makes migration a little more robust in case the same SQL scripts are applied to different databases than those used to generate the migration scripts for.
`protected boolean`	`isExceptionErrorCodeMatching(SQLException ex, int... codes)`	Checks if the exception's error code equals given number(s).
`protected boolean`	`isExceptionStateMatching(SQLException ex, String... states)`	Checks if the exception's state equals given string(s).
`protected boolean`	`isExceptionStateStartingWith(SQLException ex, String... prefixes)`	Checks if the exception's state starts with a given string(s).
`boolean`	`isFilteredIndexSupported()`	Returns whether backend supports filtered indexes.
`boolean`	`isFunctionBasedIndexSupported()`	Returns whether function based indexes are supported.
`boolean`	`isMatchingName(String name)`	Checks whether the backend belongs to the given name.
`boolean`	`isReleaseSavepointSupported()`	Returns whether the backend supports releasing savepoints explicitly.
`boolean`	`isReservedSchemaName(String name)`	Checks whether this is a reserved schema name for this backend.
`boolean`	`isReservedTableName(String name)`	Checks whether this a reserved table name for this backend. Applies only to tables.
`boolean`	`isTemporaryName(String name)`	Checks whether this is a temporary name. Returns whether an entity-, attribute- or index-name is temporary and should not be taken into account for migration or even used in the model. Depending on the backend, temporary names start with an underscore or some other lead string.
`boolean`	`isTransientTransactionException(SQLException ex)`	Determines whether exception is transient and retrying the transaction may succeed. Typical transient exceptions are thrown when a deadlock is detected or when serialized transaction isolation is used.
`SqlType[]`	`jdbcTypeToSqlType(int jdbcType, int size, int scale)`	Converts the JDBC data type integer to a tentackle backend SqlTypes.
`boolean`	`needAliasForSubselect()`	Returns whether backend needs an alias for a subselect.
`boolean`	`needSetLongWorkaround()`	Checks whether we need a workaround for the (Ingres) setLong-Bug.
`boolean`	`needTxForFetchsize()`	Checks for the (postgres) bug that fetchsize is ignored if not within a new transaction.
`protected String`	`normalizeDefault(String str)`	Normalize the default string to compare.
`String`	`optimizeSql(String sql)`	Optimize SQL code. Replace WHERE 1=1 AND/OR to WHERE.
`void`	`setArray(PreparedStatement statement, int pos, SqlType type, Collection<?> elements, String operator)`	Sets an array parameter in a prepared statement.
`void`	`setDropIfExistsEnabled(boolean dropIfExistsEnabled)`	Some database support drop index/constraint/column IF EXISTS. This may be useful if migration scripts are generated against non-production databases that contain test indexes etc... Notice, that those temporary DDL changes should better use the temporary prefix (see `Backend.isTemporaryName(String)` in order to be ignored by the migrator.
`String`	`sqlAddColumn(String tableName, String columnName, String comment, SqlType sqlType, int size, int scale, boolean nullable, Object defaultValue)`	Generates sql code to add a column.
`String`	`sqlAlterColumnComment(String tableName, String columnName, String comment)`	Generates SQL code to alter the comment for an attribute.
`String`	`sqlAlterColumnDefault(String tableName, String columnName, SqlType sqlType, Object defaultValue)`	Generates sql code to change the default value a column.
`String`	`sqlAlterColumnNullConstraint(String tableName, String columnName, boolean nullable)`	Generates sql code to change the null-constraint of a column.
`String`	`sqlAlterColumnType(String tableName, String columnName, String comment, SqlType sqlType, int size, int scale, boolean nullable, Object defaultValue)`	Generates sql code to change the datatype of a column.
`String`	`sqlAlterTableComment(String tableName, String comment)`	Generates SQL code to alter the comment for a table.
`String`	`sqlAsBeforeTableAlias()`	Gets the string before the table alias. In most databases the " AS " is optional and some don't accept it all.
`String`	`sqlComment(String text)`	Create comment sql code that is interpreted as a comment by the backend.
`String`	`sqlCreateColumn(String columnName, String comment, SqlType sqlType, int size, int scale, boolean nullable, Object defaultValue, boolean primaryKey, boolean withTrailingComma)`	Generates the attribute definition of a CREATE TABLE statement.
`String`	`sqlCreateColumnComment(String tableName, String columnName, String comment)`	Generates SQL code to create the comment for an attribute.
`String`	`sqlCreateIndex(String tableName, String indexName, boolean unique, String filterCondition, String... columnNames)`	Generates the CREATE INDEX statement.
`protected String`	`sqlCreateTableAttributeWithoutComment(String columnName, SqlType sqlType, int size, int scale, boolean nullable, Object defaultValue, boolean primaryKey, boolean withTrailingComma)`	Generates the attribute definition of a CREATE TABLE statement.
`String`	`sqlCreateTableClosing(String tableName, String comment)`	Generates the last line of a CREATE TABLE statement.
`String`	`sqlCreateTableComment(String tableName, String comment)`	Generates SQL code to create the comment for a table.
`String`	`sqlCreateTableIntro(String tableName, String comment)`	Generates the first line of a CREATE TABLE statement.
`protected String`	`sqlCreateTableIntroWithoutComment(String tableName)`	Generates the first line of a CREATE TABLE statement.
`String`	`sqlDropColumn(String tableName, String columnName)`	Generates sql code to drop a column.
`String`	`sqlDropIndex(String schemaName, String tableNameWithoutSchema, String indexName)`	Generates the DROP INDEX statement.
`String`	`sqlDropTable(String schemaName, String tableNameWithoutSchema)`	Generates the DROP TABLE statement.
`String`	`sqlFunction(String functionName, String expression)`	Creates an sql function expression.
`String`	`sqlJoin(JoinType type, String joinedTableName, String joinedTableAlias, String join)`	Creates a join clause.
`void`	`sqlJoinSelects(JoinType type, boolean addColumns, StringBuilder select, String joinSelect, String joinSelectIdAlias, String joinAlias, String join)`	Generate SQL code for joining a table to an existing select.
`String`	`sqlJoinSelects(JoinType type, boolean addColumns, String select, String joinSelect, String joinSelectIdAlias, String joinAlias, String join)`	Generate SQL code for joining a table to an existing select.
`String`	`sqlRenameAndAlterColumnType(String tableName, String oldColumnName, String newColumnName, String comment, SqlType sqlType, int size, int scale, boolean nullable, Object defaultValue)`	Generates sql code to rename a column.
`String`	`sqlRenameColumn(String tableName, String oldColumnName, String newColumnName)`	Generates sql code to rename a column.
`String`	`sqlRenameIndex(String tableName, String oldIndexName, String newIndexName)`	Generates sql code to rename an index.
`String`	`sqlRenameTable(String tableName, String newTableName)`	Generate sql code to rename a table.
`boolean`	`sqlRequiresExtraCommit()`	According to the JDBC-specs `Connection.setAutoCommit(boolean)`(true) should commit, but some backends require an extra `Connection.commit()`.
`boolean`	`sqlResultSetIsClosedSupported()`	Determines whether the jdbc driver supports `ResultSet.isClosed()`.
`String`	`sqlTypeToString(SqlType sqlType, int size)`	Converts the java SQL-type to the database type name.
`String`	`sqlUpdateToNotNull(String tableName, String columnName, SqlType sqlType, Object defaultValue)`	Generates code to update a column to a non-null value.
`String`	`toInternalType(String sqlTypeName)`	Converts a backend specific type name to an internal name used by driver specific methods.
`String`	`toQuotedString(String str)`	Converts a string to a string enclosed in single quotes.
`String`	`toString()`
`String`	`valueToLiteral(SqlType sqlType, Object value)`	Conberts a type and value to a literal string.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.tentackle.sql.Backend
buildSelectSql, getBackendId, getDriverClassName, getName, getReservedWords, isMatchingUrl, setLeadingSelectParameters, setTrailingSelectParameters, sqlCreateForeignKey, sqlDropForeignKey, sqlNextFromSequene, supportsSequences

- Field Detail
  - TYPE_BIGINT
```
protected static final String TYPE_BIGINT
```
    See Also:
    
    Constant Field Values
  - TYPE_BIT
```
protected static final String TYPE_BIT
```
    See Also:
    
    Constant Field Values
  - TYPE_BLOB
```
protected static final String TYPE_BLOB
```
    See Also:
    
    Constant Field Values
  - TYPE_CLOB
```
protected static final String TYPE_CLOB
```
    See Also:
    
    Constant Field Values
  - TYPE_BOOL
```
protected static final String TYPE_BOOL
```
    See Also:
    
    Constant Field Values
  - TYPE_BOOLEAN
```
protected static final String TYPE_BOOLEAN
```
    See Also:
    
    Constant Field Values
  - TYPE_BYTEA
```
protected static final String TYPE_BYTEA
```
    See Also:
    
    Constant Field Values
  - TYPE_BYTE
```
protected static final String TYPE_BYTE
```
    See Also:
    
    Constant Field Values
  - TYPE_CHAR_1
```
protected static final String TYPE_CHAR_1
```
    See Also:
    
    Constant Field Values
  - TYPE_DATE
```
protected static final String TYPE_DATE
```
    See Also:
    
    Constant Field Values
  - TYPE_DATETIME
```
protected static final String TYPE_DATETIME
```
    See Also:
    
    Constant Field Values
  - TYPE_DATETIME_YEAR_TO_SECOND
```
protected static final String TYPE_DATETIME_YEAR_TO_SECOND
```
    See Also:
    
    Constant Field Values
  - TYPE_DECIMAL
```
protected static final String TYPE_DECIMAL
```
    See Also:
    
    Constant Field Values
  - TYPE_DECIMAL_19
```
protected static final String TYPE_DECIMAL_19
```
    See Also:
    
    Constant Field Values
  - TYPE_DOUBLE
```
protected static final String TYPE_DOUBLE
```
    See Also:
    
    Constant Field Values
  - TYPE_FLOAT
```
protected static final String TYPE_FLOAT
```
    See Also:
    
    Constant Field Values
  - TYPE_FLOAT4
```
protected static final String TYPE_FLOAT4
```
    See Also:
    
    Constant Field Values
  - TYPE_FLOAT8
```
protected static final String TYPE_FLOAT8
```
    See Also:
    
    Constant Field Values
  - TYPE_INT
```
protected static final String TYPE_INT
```
    See Also:
    
    Constant Field Values
  - TYPE_INT2
```
protected static final String TYPE_INT2
```
    See Also:
    
    Constant Field Values
  - TYPE_INT4
```
protected static final String TYPE_INT4
```
    See Also:
    
    Constant Field Values
  - TYPE_INT8
```
protected static final String TYPE_INT8
```
    See Also:
    
    Constant Field Values
  - TYPE_INTEGER
```
protected static final String TYPE_INTEGER
```
    See Also:
    
    Constant Field Values
  - TYPE_NCHAR_1
```
protected static final String TYPE_NCHAR_1
```
    See Also:
    
    Constant Field Values
  - TYPE_NUMBER
```
protected static final String TYPE_NUMBER
```
    See Also:
    
    Constant Field Values
  - TYPE_NUMBER_1
```
protected static final String TYPE_NUMBER_1
```
    See Also:
    
    Constant Field Values
  - TYPE_NUMBER_5
```
protected static final String TYPE_NUMBER_5
```
    See Also:
    
    Constant Field Values
  - TYPE_NUMBER_10
```
protected static final String TYPE_NUMBER_10
```
    See Also:
    
    Constant Field Values
  - TYPE_NUMBER_19
```
protected static final String TYPE_NUMBER_19
```
    See Also:
    
    Constant Field Values
  - TYPE_NVARCHAR
```
protected static final String TYPE_NVARCHAR
```
    See Also:
    
    Constant Field Values
  - TYPE_NVARCHAR_MAX
```
protected static final String TYPE_NVARCHAR_MAX
```
    See Also:
    
    Constant Field Values
  - TYPE_REAL
```
protected static final String TYPE_REAL
```
    See Also:
    
    Constant Field Values
  - TYPE_TEXT
```
protected static final String TYPE_TEXT
```
    See Also:
    
    Constant Field Values
  - TYPE_TIME
```
protected static final String TYPE_TIME
```
    See Also:
    
    Constant Field Values
  - TYPE_TIMESTAMP
```
protected static final String TYPE_TIMESTAMP
```
    See Also:
    
    Constant Field Values
  - TYPE_TINYINT
```
protected static final String TYPE_TINYINT
```
    See Also:
    
    Constant Field Values
  - TYPE_SMALLFLOAT
```
protected static final String TYPE_SMALLFLOAT
```
    See Also:
    
    Constant Field Values
  - TYPE_SMALLINT
```
protected static final String TYPE_SMALLINT
```
    See Also:
    
    Constant Field Values
  - TYPE_VARBINARY_MAX
```
protected static final String TYPE_VARBINARY_MAX
```
    See Also:
    
    Constant Field Values
  - TYPE_VARCHAR
```
protected static final String TYPE_VARCHAR
```
    See Also:
    
    Constant Field Values
- Constructor Detail
  - AbstractBackend
```
public AbstractBackend()
```
- Method Detail
  - isMatchingName
```
public boolean isMatchingName(String name)
```
    Description copied from interface: Backend
    
    Checks whether the backend belongs to the given name.
    
    Specified by:
    
    isMatchingName in interface Backend
    
    Parameters:
    
    name - the backend's name
    
    Returns:
    
    true if matches
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
  - createConnection
```
public Connection createConnection(String url,
                                   String username,
                                   char[] password)
                            throws SQLException
```
    Description copied from interface: Backend
    
    Creates a jdbc connection.
    
    Specified by:
    
    createConnection in interface Backend
    
    Parameters:
    
    url - the jdbc url
    
    username - the username
    
    password - the password
    
    Returns:
    
    the created connection
    
    Throws:
    
    SQLException - if connection could not be established
  - getMetaData
```
public DatabaseMetaData[] getMetaData(BackendInfo backendInfo)
                               throws SQLException
```
    Description copied from interface: Backend
    
    Gets the metadata from the backend.
    Important: the connection of the metadata is open!
    
    Specified by:
    
    getMetaData in interface Backend
    
    Parameters:
    
    backendInfo - the backend info
    
    Returns:
    
    the metadata, may be more than one if schemas set in backendInfo
    
    Throws:
    
    SQLException - if failed
  - getTableHeaders
```
public List<DatabaseMetaDataTableHeader> getTableHeaders(DatabaseMetaData metaData)
                                                  throws SQLException
```
    Description copied from interface: Backend
    
    Gets all table headers for a given metadata.
    
    Specified by:
    
    getTableHeaders in interface Backend
    
    Parameters:
    
    metaData - the database metadata
    
    Returns:
    
    the list of table headers
    
    Throws:
    
    SQLException - if failed
  - isTemporaryName
```
public boolean isTemporaryName(String name)
```
    Description copied from interface: Backend
    
    Checks whether this is a temporary name.
    Returns whether an entity-, attribute- or index-name is temporary and should not be taken into account for migration or even used in the model.
    Depending on the backend, temporary names start with an underscore or some other lead string.
    
    Specified by:
    
    isTemporaryName in interface Backend
    
    Parameters:
    
    name - the name
    
    Returns:
    
    true temporary (invalid) name
  - isReservedTableName
```
public boolean isReservedTableName(String name)
```
    Description copied from interface: Backend
    
    Checks whether this a reserved table name for this backend.
    Applies only to tables. Not to be mixed up with Backend.getReservedWords().
    Useful to avoid conflicts with naming conventions for backend specific things, such as snapshots.
    
    Specified by:
    
    isReservedTableName in interface Backend
    
    Parameters:
    
    name - the table name
    
    Returns:
    
    true if reserved by backend
  - isReservedSchemaName
```
public boolean isReservedSchemaName(String name)
```
    Description copied from interface: Backend
    
    Checks whether this is a reserved schema name for this backend.
    
    Specified by:
    
    isReservedSchemaName in interface Backend
    
    Parameters:
    
    name - the schema name
    
    Returns:
    
    true if reserved by backend
  - getEmptyString
```
public String getEmptyString()
```
    Description copied from interface: Backend
    
    Gets the empty string.
    Some dbms (most famous: Oracle) handle empty strings as null. In such cases the empty string (e.g. Oracle) may consist of a single blank or whatever.
    
    Specified by:
    
    getEmptyString in interface Backend
    
    Returns:
    
    the empty string (never null)
  - sqlAsBeforeTableAlias
```
public String sqlAsBeforeTableAlias()
```
    Description copied from interface: Backend
    
    Gets the string before the table alias.
    In most databases the " AS " is optional and some don't accept it all.
    
    Specified by:
    
    sqlAsBeforeTableAlias in interface Backend
    
    Returns:
    
    the as-string
  - needAliasForSubselect
```
public boolean needAliasForSubselect()
```
    Description copied from interface: Backend
    
    Returns whether backend needs an alias for a subselect.
    
    Specified by:
    
    needAliasForSubselect in interface Backend
    
    Returns:
    
    true if subselect needs an alias.
  - sqlRequiresExtraCommit
```
public boolean sqlRequiresExtraCommit()
```
    Description copied from interface: Backend
    
    According to the JDBC-specs Connection.setAutoCommit(boolean)(true) should commit, but some backends require an extra Connection.commit().
    
    Specified by:
    
    sqlRequiresExtraCommit in interface Backend
    
    Returns:
    
    true if the database needs an extra commit
  - sqlResultSetIsClosedSupported
```
public boolean sqlResultSetIsClosedSupported()
```
    Description copied from interface: Backend
    
    Determines whether the jdbc driver supports ResultSet.isClosed().
    
    Specified by:
    
    sqlResultSetIsClosedSupported in interface Backend
    
    Returns:
    
    true if the driver supports it
  - sqlComment
```
public String sqlComment(String text)
```
    Description copied from interface: Backend
    
    Create comment sql code that is interpreted as a comment by the backend.
    
    Specified by:
    
    sqlComment in interface Backend
    
    Parameters:
    
    text - any text, single or multiline
    
    Returns:
    
    the comment, null if text was null
  - sqlJoin
```
public String sqlJoin(JoinType type,
                      String joinedTableName,
                      String joinedTableAlias,
                      String join)
```
    Description copied from interface: Backend
    
    Creates a join clause.
    
    Specified by:
    
    sqlJoin in interface Backend
    
    Parameters:
    
    type - the join type
    
    joinedTableName - the joined tablename
    
    joinedTableAlias - the joined table alias, null if none
    
    join - the join expression
    
    Returns:
    
    the sql code
  - sqlFunction
```
public String sqlFunction(String functionName,
                          String expression)
```
    Description copied from interface: Backend
    Creates an sql function expression.
    Example:
    sqlFunction("max", CN_ID) --> "MAX(id)"
    Specified by:
    
    sqlFunction in interface Backend
    
    Parameters:
    
    functionName - the function name, will be translated to uppercase
    
    expression - the expression, may be null
    
    Returns:
    
    the sql code
  - getCoalesceKeyword
```
public String getCoalesceKeyword()
```
    Description copied from interface: Backend
    
    Gets the keyword for the COALESCE function.
    
    Specified by:
    
    getCoalesceKeyword in interface Backend
    
    Returns:
    
    the keyword
  - allowsExpressionsReferringToTablesBeingUpdated
```
public boolean allowsExpressionsReferringToTablesBeingUpdated()
```
    Description copied from interface: Backend
    
    Determines whether backend allows expressions referring to tables being updated.
    
    Specified by:
    
    allowsExpressionsReferringToTablesBeingUpdated in interface Backend
    
    Returns:
    
    true if allowed
  - needSetLongWorkaround
```
public boolean needSetLongWorkaround()
```
    Description copied from interface: Backend
    
    Checks whether we need a workaround for the (Ingres) setLong-Bug.
    
    Specified by:
    
    needSetLongWorkaround in interface Backend
    
    Returns:
    
    true if workaround needed
  - needTxForFetchsize
```
public boolean needTxForFetchsize()
```
    Description copied from interface: Backend
    
    Checks for the (postgres) bug that fetchsize is ignored if not within a new transaction.
    
    Specified by:
    
    needTxForFetchsize in interface Backend
    
    Returns:
    
    true if start tx
  - isConstraintException
```
public boolean isConstraintException(SQLException ex)
```
    Description copied from interface: Backend
    
    Determines whether exception is a constraint violation.
    
    Specified by:
    
    isConstraintException in interface Backend
    
    Parameters:
    
    ex - the exception
    
    Returns:
    
    true if constraint violation
  - isCommunicationLinkException
```
public boolean isCommunicationLinkException(SQLException ex)
```
    Description copied from interface: Backend
    
    Determines whether exception is a communication error.
    
    Specified by:
    
    isCommunicationLinkException in interface Backend
    
    Parameters:
    
    ex - the exception
    
    Returns:
    
    true if comlink down or alike
  - isTransientTransactionException
```
public boolean isTransientTransactionException(SQLException ex)
```
    Description copied from interface: Backend
    
    Determines whether exception is transient and retrying the transaction may succeed.
    Typical transient exceptions are thrown when a deadlock is detected or when serialized transaction isolation is used.
    Other transient errors are not covered by this method (e.g. connection timeouts, etc...).
    
    Specified by:
    
    isTransientTransactionException in interface Backend
    
    Parameters:
    
    ex - the exception
    
    Returns:
    
    true if retrying the transaction may succeed
  - getMaxSize
```
public int getMaxSize(SqlType sqlType)
```
    Description copied from interface: Backend
    
    Returns the maximum size for a given SQL-type.
    
    Specified by:
    
    getMaxSize in interface Backend
    
    Parameters:
    
    sqlType - the SQL-type
    
    Returns:
    
    the maximum size, 0 if unlimited, -1 if type without size
  - getMaxScale
```
public int getMaxScale(SqlType sqlType,
                       int size)
```
    Description copied from interface: Backend
    
    Returns the maximum scale for a given SQL-type and size.
    
    Specified by:
    
    getMaxScale in interface Backend
    
    Parameters:
    
    sqlType - the SQL-type
    
    size - the size, 0 if unlimited
    
    Returns:
    
    the maximum scale, 0 if unlimited
  - getDefaultSize
```
public int getDefaultSize(SqlType sqlType)
```
    Description copied from interface: Backend
    
    Gets the default size if no size given in model.
    
    Specified by:
    
    getDefaultSize in interface Backend
    
    Parameters:
    
    sqlType - the SQL-type
    
    Returns:
    
    the default size, 0 if no default size
  - getDefaultSchema
```
public String getDefaultSchema()
```
    Description copied from interface: Backend
    
    Gets the default schema name.
    Some backends store the objects in a default schema, if no explicit schema is given.
    
    Specified by:
    
    getDefaultSchema in interface Backend
    
    Returns:
    
    the defailt schema, null if none
  - getModelMetaData
```
public ModelMetaData getModelMetaData(DatabaseMetaData[] metaData,
                                      String[] schemas,
                                      String... tableNames)
```
    Description copied from interface: Backend
    
    Retrieves the metadata.
    
    Specified by:
    
    getModelMetaData in interface Backend
    
    Parameters:
    
    metaData - the meta data for the whole database
    
    schemas - the optional schemas to filter tables, null if no filter
    
    tableNames - the tables of the model
    
    Returns:
    
    the meta data, null if no such table
  - getTableMetaData
```
public TableMetaData getTableMetaData(ModelMetaData modelMetaData,
                                      String tableName)
```
    Description copied from interface: Backend
    
    Gets the table meta data for a given table name.
    
    Specified by:
    
    getTableMetaData in interface Backend
    
    Parameters:
    
    modelMetaData - the model the table belongs to
    
    tableName - the model's table name
    
    Returns:
    
    the table data
  - createTableMetaData
```
public TableMetaData createTableMetaData(ModelMetaData modelMetaData,
                                         String tableName)
```
    Description copied from interface: Backend
    
    Creates a meta data instance.
    
    Specified by:
    
    createTableMetaData in interface Backend
    
    Parameters:
    
    modelMetaData - the whole meta data
    
    tableName - the model's table name
    
    Returns:
    
    the meta data
  - createColumnMetaData
```
public ColumnMetaData createColumnMetaData(TableMetaData tableMetaData)
```
    Description copied from interface: Backend
    
    Creates a column meta data instance.
    
    Specified by:
    
    createColumnMetaData in interface Backend
    
    Parameters:
    
    tableMetaData - the table meta data this column belongs to
    
    Returns:
    
    the meta data
  - createIndexMetaData
```
public IndexMetaData createIndexMetaData(TableMetaData tableMetaData)
```
    Description copied from interface: Backend
    
    Creates an index meta data instance.
    
    Specified by:
    
    createIndexMetaData in interface Backend
    
    Parameters:
    
    tableMetaData - the table meta data this index belongs to
    
    Returns:
    
    the meta data
  - createIndexColumnMetaData
```
public IndexColumnMetaData createIndexColumnMetaData(IndexMetaData indexMetaData)
```
    Description copied from interface: Backend
    
    Creates an index column meta data instance.
    
    Specified by:
    
    createIndexColumnMetaData in interface Backend
    
    Parameters:
    
    indexMetaData - the meta meta data this column belongs to
    
    Returns:
    
    the meta data
  - sqlCreateTableIntro
```
public String sqlCreateTableIntro(String tableName,
                                  String comment)
```
    Description copied from interface: Backend
    
    Generates the first line of a CREATE TABLE statement.
    
    Specified by:
    
    sqlCreateTableIntro in interface Backend
    
    Parameters:
    
    tableName - the tablename with optional schema separated by a dot
    
    comment - optional comment, null if none
    
    Returns:
    
    the SQL code including the opening bracket
  - sqlCreateTableClosing
```
public String sqlCreateTableClosing(String tableName,
                                    String comment)
```
    Description copied from interface: Backend
    
    Generates the last line of a CREATE TABLE statement.
    
    Specified by:
    
    sqlCreateTableClosing in interface Backend
    
    Parameters:
    
    tableName - the tablename with optional schema separated by a dot
    
    comment - optional comment, null if none
    
    Returns:
    
    the SQL code including the closing bracket
  - sqlCreateTableComment
```
public String sqlCreateTableComment(String tableName,
                                    String comment)
```
    Description copied from interface: Backend
    
    Generates SQL code to create the comment for a table.
    
    Specified by:
    
    sqlCreateTableComment in interface Backend
    
    Parameters:
    
    tableName - the table name
    
    comment - optional comment, null if none
    
    Returns:
    
    the SQL code, empty string if comment is created via Backend.sqlCreateTableIntro(java.lang.String, java.lang.String) or Backend.sqlCreateTableClosing(java.lang.String, java.lang.String)
  - sqlAlterTableComment
```
public String sqlAlterTableComment(String tableName,
                                   String comment)
```
    Description copied from interface: Backend
    
    Generates SQL code to alter the comment for a table.
    
    Specified by:
    
    sqlAlterTableComment in interface Backend
    
    Parameters:
    
    tableName - the table name
    
    comment - optional comment, null to clear
    
    Returns:
    
    the SQL code
  - columnTypeToString
```
public String columnTypeToString(SqlType sqlType,
                                 int size,
                                 int scale)
```
    Description copied from interface: Backend
    
    Converts an sqltype, size and scale to a database type declaration.
    
    Specified by:
    
    columnTypeToString in interface Backend
    
    Parameters:
    
    sqlType - the SQL type
    
    size - the size
    
    scale - the scale
    
    Returns:
    
    the type definition
  - columnTypeNullDefaultToString
```
public String columnTypeNullDefaultToString(String columnName,
                                            SqlType sqlType,
                                            int size,
                                            int scale,
                                            boolean nullable,
                                            Object defaultValue)
```
    Description copied from interface: Backend
    
    Converts an sqltype, size, scale, nullable and default value to a database type declaration.
    
    Specified by:
    
    columnTypeNullDefaultToString in interface Backend
    
    Parameters:
    
    columnName - the database column name
    
    sqlType - the JDBC sql type
    
    size - the optional size
    
    scale - the optional scale
    
    nullable - true if NULL, else NOT NULL
    
    defaultValue - the optional default value
    
    Returns:
    
    the SQL code
  - valueToLiteral
```
public String valueToLiteral(SqlType sqlType,
                             Object value)
```
    Description copied from interface: Backend
    
    Conberts a type and value to a literal string.
    
    Specified by:
    
    valueToLiteral in interface Backend
    
    Parameters:
    
    sqlType - the sql type
    
    value - the value
    
    Returns:
    
    the constant
  - sqlCreateColumn
```
public String sqlCreateColumn(String columnName,
                              String comment,
                              SqlType sqlType,
                              int size,
                              int scale,
                              boolean nullable,
                              Object defaultValue,
                              boolean primaryKey,
                              boolean withTrailingComma)
```
    Description copied from interface: Backend
    
    Generates the attribute definition of a CREATE TABLE statement.
    
    Specified by:
    
    sqlCreateColumn in interface Backend
    
    Parameters:
    
    columnName - the database column name
    
    comment - optional comment, null if none
    
    sqlType - the JDBC sql type
    
    size - the optional size
    
    scale - the optional scale
    
    nullable - true if NULL, else NOT NULL
    
    defaultValue - the optional default value
    
    primaryKey - true if this is a primary key
    
    withTrailingComma - true if append a comma
    
    Returns:
    
    the SQL code
  - isDefaultEqual
```
public boolean isDefaultEqual(ColumnMetaData column,
                              SqlType sqlType,
                              Object defaultValue)
```
    Description copied from interface: Backend
    
    Checks whether the column's default corresponds to the model's default value.
    
    Specified by:
    
    isDefaultEqual in interface Backend
    
    Parameters:
    
    column - the column to inspect
    
    sqlType - the sql type
    
    defaultValue - the model's default value
    
    Returns:
    
    true if same
  - getMigrationStrategy
```
public MigrationStrategy[] getMigrationStrategy(ColumnMetaData column,
                                                String columnName,
                                                String comment,
                                                SqlType sqlType,
                                                int size,
                                                int scale,
                                                boolean nullable,
                                                Object defaultValue)
```
    Description copied from interface: Backend
    
    Determines the best migration strategy.
    
    Specified by:
    
    getMigrationStrategy in interface Backend
    
    Parameters:
    
    column - old column meta data
    
    columnName - new column name
    
    comment - new comment
    
    sqlType - new sql type
    
    size - new size
    
    scale - new scale
    
    nullable - new nullable
    
    defaultValue - new default
    
    Returns:
    
    the strategies in order to achieve the migration
  - sqlRenameTable
```
public String sqlRenameTable(String tableName,
                             String newTableName)
```
    Description copied from interface: Backend
    
    Generate sql code to rename a table.
    
    Specified by:
    
    sqlRenameTable in interface Backend
    
    Parameters:
    
    tableName - the old tablename (with leading schema, if any)
    
    newTableName - the new tablename (without schema)
    
    Returns:
    
    the SQL code
  - sqlRenameColumn
```
public String sqlRenameColumn(String tableName,
                              String oldColumnName,
                              String newColumnName)
```
    Description copied from interface: Backend
    
    Generates sql code to rename a column.
    
    Specified by:
    
    sqlRenameColumn in interface Backend
    
    Parameters:
    
    tableName - the tablename
    
    oldColumnName - the old column name
    
    newColumnName - the new column name
    
    Returns:
    
    the SQL code, null if need full spec sqlRenameAndAlterColumnType below
  - sqlRenameIndex
```
public String sqlRenameIndex(String tableName,
                             String oldIndexName,
                             String newIndexName)
```
    Description copied from interface: Backend
    
    Generates sql code to rename an index.
    
    Specified by:
    
    sqlRenameIndex in interface Backend
    
    Parameters:
    
    tableName - the tablename
    
    oldIndexName - the old column name
    
    newIndexName - the new column name
    
    Returns:
    
    the SQL code, null if not supported by the backend and we need to drop and create
  - sqlRenameAndAlterColumnType
```
public String sqlRenameAndAlterColumnType(String tableName,
                                          String oldColumnName,
                                          String newColumnName,
                                          String comment,
                                          SqlType sqlType,
                                          int size,
                                          int scale,
                                          boolean nullable,
                                          Object defaultValue)
```
    Description copied from interface: Backend
    
    Generates sql code to rename a column.
    
    Specified by:
    
    sqlRenameAndAlterColumnType in interface Backend
    
    Parameters:
    
    tableName - the tablename
    
    oldColumnName - the old column name
    
    newColumnName - the new column name
    
    comment - optional comment, null if none
    
    sqlType - the JDBC sql type
    
    size - the optional size
    
    scale - the optional scale
    
    nullable - true if NULL, else NOT NULL
    
    defaultValue - the optional default value
    
    Returns:
    
    the SQL code
  - sqlAddColumn
```
public String sqlAddColumn(String tableName,
                           String columnName,
                           String comment,
                           SqlType sqlType,
                           int size,
                           int scale,
                           boolean nullable,
                           Object defaultValue)
```
    Description copied from interface: Backend
    
    Generates sql code to add a column.
    
    Specified by:
    
    sqlAddColumn in interface Backend
    
    Parameters:
    
    tableName - the tablename
    
    columnName - the new column name
    
    comment - optional comment, null if none
    
    sqlType - the JDBC sql type
    
    size - the optional size
    
    scale - the optional scale
    
    nullable - true if NULL, else NOT NULL
    
    defaultValue - the optional default value
    
    Returns:
    
    the SQL code
  - sqlDropColumn
```
public String sqlDropColumn(String tableName,
                            String columnName)
```
    Description copied from interface: Backend
    
    Generates sql code to drop a column.
    
    Specified by:
    
    sqlDropColumn in interface Backend
    
    Parameters:
    
    tableName - the tablename
    
    columnName - the new column name
    
    Returns:
    
    the SQL code
  - sqlAlterColumnType
```
public String sqlAlterColumnType(String tableName,
                                 String columnName,
                                 String comment,
                                 SqlType sqlType,
                                 int size,
                                 int scale,
                                 boolean nullable,
                                 Object defaultValue)
```
    Description copied from interface: Backend
    
    Generates sql code to change the datatype of a column.
    
    Specified by:
    
    sqlAlterColumnType in interface Backend
    
    Parameters:
    
    tableName - the tablename
    
    columnName - the new column name
    
    comment - optional comment, null if none
    
    sqlType - the JDBC sql type
    
    size - the optional size
    
    scale - the optional scale
    
    nullable - true if NULL, else NOT NULL
    
    defaultValue - the optional default value
    
    Returns:
    
    the SQL code
  - sqlAlterColumnNullConstraint
```
public String sqlAlterColumnNullConstraint(String tableName,
                                           String columnName,
                                           boolean nullable)
```
    Description copied from interface: Backend
    
    Generates sql code to change the null-constraint of a column.
    
    Specified by:
    
    sqlAlterColumnNullConstraint in interface Backend
    
    Parameters:
    
    tableName - the tablename
    
    columnName - the new column name
    
    nullable - true if NULL, else NOT NULL
    
    Returns:
    
    the SQL code, null if need Backend.sqlAlterColumnType(java.lang.String, java.lang.String, java.lang.String, org.tentackle.sql.SqlType, int, int, boolean, java.lang.Object)
  - sqlUpdateToNotNull
```
public String sqlUpdateToNotNull(String tableName,
                                 String columnName,
                                 SqlType sqlType,
                                 Object defaultValue)
```
    Description copied from interface: Backend
    
    Generates code to update a column to a non-null value.
    
    Specified by:
    
    sqlUpdateToNotNull in interface Backend
    
    Parameters:
    
    tableName - the tablename
    
    columnName - the column name
    
    sqlType - the sql type
    
    defaultValue - the optional default value if defined in the model
    
    Returns:
    
    the SQL code
  - sqlAlterColumnDefault
```
public String sqlAlterColumnDefault(String tableName,
                                    String columnName,
                                    SqlType sqlType,
                                    Object defaultValue)
```
    Description copied from interface: Backend
    
    Generates sql code to change the default value a column.
    
    Specified by:
    
    sqlAlterColumnDefault in interface Backend
    
    Parameters:
    
    tableName - the tablename
    
    columnName - the new column name
    
    sqlType - the JDBC sql type
    
    defaultValue - the optional default value
    
    Returns:
    
    the SQL code, null if need Backend.sqlAlterColumnType(java.lang.String, java.lang.String, java.lang.String, org.tentackle.sql.SqlType, int, int, boolean, java.lang.Object)
  - sqlCreateColumnComment
```
public String sqlCreateColumnComment(String tableName,
                                     String columnName,
                                     String comment)
```
    Description copied from interface: Backend
    
    Generates SQL code to create the comment for an attribute.
    
    Specified by:
    
    sqlCreateColumnComment in interface Backend
    
    Parameters:
    
    tableName - the table name
    
    columnName - the column name
    
    comment - optional comment, null if none
    
    Returns:
    
    the SQL code, empty string if comment is created via Backend.sqlCreateColumn(java.lang.String, java.lang.String, org.tentackle.sql.SqlType, int, int, boolean, java.lang.Object, boolean, boolean)
  - sqlAlterColumnComment
```
public String sqlAlterColumnComment(String tableName,
                                    String columnName,
                                    String comment)
```
    Description copied from interface: Backend
    
    Generates SQL code to alter the comment for an attribute.
    
    Specified by:
    
    sqlAlterColumnComment in interface Backend
    
    Parameters:
    
    tableName - the table name
    
    columnName - the column name
    
    comment - optional comment, null to clear
    
    Returns:
    
    the SQL code, null if use Backend.sqlRenameAndAlterColumnType(java.lang.String, java.lang.String, java.lang.String, java.lang.String, org.tentackle.sql.SqlType, int, int, boolean, java.lang.Object) instead
  - sqlTypeToString
```
public String sqlTypeToString(SqlType sqlType,
                              int size)
```
    Description copied from interface: Backend
    
    Converts the java SQL-type to the database type name.
    
    Specified by:
    
    sqlTypeToString in interface Backend
    
    Parameters:
    
    sqlType - the java sql type
    
    size - the column's size
    
    Returns:
    
    the corresponding type string
  - sqlCreateIndex
```
public String sqlCreateIndex(String tableName,
                             String indexName,
                             boolean unique,
                             String filterCondition,
                             String... columnNames)
```
    Description copied from interface: Backend
    
    Generates the CREATE INDEX statement.
    
    Specified by:
    
    sqlCreateIndex in interface Backend
    
    Parameters:
    
    tableName - the table name
    
    indexName - the name of the index
    
    unique - true if index is unique
    
    filterCondition - the filter condition (null if none)
    
    columnNames - the column names (with a leading '-' if descending). Simple function-based indexes are also supported.
    
    Returns:
    
    the SQL code
  - sqlDropIndex
```
public String sqlDropIndex(String schemaName,
                           String tableNameWithoutSchema,
                           String indexName)
```
    Description copied from interface: Backend
    
    Generates the DROP INDEX statement.
    
    Specified by:
    
    sqlDropIndex in interface Backend
    
    Parameters:
    
    schemaName - the optional schema, null if none
    
    tableNameWithoutSchema - the table name without the schema
    
    indexName - the name of the index
    
    Returns:
    
    the SQL code
  - sqlDropTable
```
public String sqlDropTable(String schemaName,
                           String tableNameWithoutSchema)
```
    Description copied from interface: Backend
    
    Generates the DROP TABLE statement.
    
    Specified by:
    
    sqlDropTable in interface Backend
    
    Parameters:
    
    schemaName - the optional schema, null if none
    
    tableNameWithoutSchema - the table name without the schema
    
    Returns:
    
    the SQL code
  - sqlJoinSelects
```
public void sqlJoinSelects(JoinType type,
                           boolean addColumns,
                           StringBuilder select,
                           String joinSelect,
                           String joinSelectIdAlias,
                           String joinAlias,
                           String join)
```
    Description copied from interface: Backend
    
    Generate SQL code for joining a table to an existing select.
    
    Specified by:
    
    sqlJoinSelects in interface Backend
    
    Parameters:
    
    type - the join type
    
    addColumns - true if columns of joined table should be added to the result set
    
    select - the original select statement
    
    joinSelect - the select to join with the original sql or just a tablename
    
    joinSelectIdAlias - extra id alias to add to the joined select, null if none
    
    joinAlias - the alias of the joined select
    
    join - the join clause
  - assertValidName
```
public void assertValidName(SqlNameType nameType,
                            String name)
```
    Description copied from interface: Backend
    
    Asserts that given string is a valid name and usage.
    
    Specified by:
    
    assertValidName in interface Backend
    
    Parameters:
    
    nameType - the type/usage of the name
    
    name - the name
  - jdbcTypeToSqlType
```
public SqlType[] jdbcTypeToSqlType(int jdbcType,
                                   int size,
                                   int scale)
```
    Description copied from interface: Backend
    
    Converts the JDBC data type integer to a tentackle backend SqlTypes.
    There may be more than one sqltype returned!
    
    Specified by:
    
    jdbcTypeToSqlType in interface Backend
    
    Parameters:
    
    jdbcType - the jdbc data type
    
    size - the column size
    
    scale - the column's scale
    
    Returns:
    
    the SqlTypes, empty array if no mapping available or no exact match (not generated by TT)
    
    See Also:
    
    Types
  - toQuotedString
```
public String toQuotedString(String str)
```
    Description copied from interface: Backend
    
    Converts a string to a string enclosed in single quotes.
    
    Specified by:
    
    toQuotedString in interface Backend
    
    Parameters:
    
    str - the string
    
    Returns:
    
    the quoted string
  - optimizeSql
```
public String optimizeSql(String sql)
```
    Description copied from interface: Backend
    
    Optimize SQL code.
    Replace WHERE 1=1 AND/OR to WHERE. Any remaining WHERE 1=1 will be removed too. If you don't want your statements getting optimized, use lowercase for those keywords.
    
    Specified by:
    
    optimizeSql in interface Backend
    
    Parameters:
    
    sql - the original sql code
    
    Returns:
    
    the optimized sql code
  - buildSelectSql
```
public String buildSelectSql(String sql,
                             boolean writeLock,
                             int limit,
                             int offset)
```
    Description copied from interface: Backend
    
    Creates a select statement string from an inner sql string.
    sqlBuilder is anything as FROM... WHERE... ORDER BY....
    It is decorated with a leading SELECT plus optional clauses like for the given parameters.
    
    Specified by:
    
    buildSelectSql in interface Backend
    
    Parameters:
    
    sql - the sql without leading SELECT.
    
    writeLock - true select should write lock
    
    limit - the limit value, ≤ 0 if no limit clause
    
    offset - the offset value, ≤ 0 if no offset clause
    
    Returns:
    
    the select statement
  - sqlJoinSelects
```
public String sqlJoinSelects(JoinType type,
                             boolean addColumns,
                             String select,
                             String joinSelect,
                             String joinSelectIdAlias,
                             String joinAlias,
                             String join)
```
    Description copied from interface: Backend
    
    Generate SQL code for joining a table to an existing select.
    
    Specified by:
    
    sqlJoinSelects in interface Backend
    
    Parameters:
    
    type - the join type
    
    addColumns - true if columns of joined table should be added to the result set
    
    select - the original select statement
    
    joinSelect - the select to join with the original sql or just a tablename
    
    joinSelectIdAlias - extra id alias to add to the joined select, null if none
    
    joinAlias - the alias of the joined select
    
    join - the join clause
    
    Returns:
    
    the select statement
  - isReleaseSavepointSupported
```
public boolean isReleaseSavepointSupported()
```
    Description copied from interface: Backend
    
    Returns whether the backend supports releasing savepoints explicitly. If not, the savepoints are released when the transaction finishs.
    
    Specified by:
    
    isReleaseSavepointSupported in interface Backend
    
    Returns:
    
    true if release is supported, else false
  - isClobSupported
```
public boolean isClobSupported()
```
    Description copied from interface: Backend
    
    Returns whether the backend support CLOB types.
    If not, it will be emulated as VARCHAR with the maximum possible size.
    
    Specified by:
    
    isClobSupported in interface Backend
    
    Returns:
    
    true if supported, false if treat as varchar
  - isFunctionBasedIndexSupported
```
public boolean isFunctionBasedIndexSupported()
```
    Description copied from interface: Backend
    
    Returns whether function based indexes are supported.
    
    Specified by:
    
    isFunctionBasedIndexSupported in interface Backend
    
    Returns:
    
    true if supported
  - isFilteredIndexSupported
```
public boolean isFilteredIndexSupported()
```
    Description copied from interface: Backend
    
    Returns whether backend supports filtered indexes.
    
    Specified by:
    
    isFilteredIndexSupported in interface Backend
    
    Returns:
    
    true if supported, false if model will raise an error if filtered index is used
  - setDropIfExistsEnabled
```
public void setDropIfExistsEnabled(boolean dropIfExistsEnabled)
```
    Description copied from interface: Backend
    
    Some database support drop index/constraint/column IF EXISTS.
    This may be useful if migration scripts are generated against non-production databases that contain test indexes etc...
    Notice, that those temporary DDL changes should better use the temporary prefix (see Backend.isTemporaryName(String) in order to be ignored by the migrator.
    
    Specified by:
    
    setDropIfExistsEnabled in interface Backend
    
    Parameters:
    
    dropIfExistsEnabled - true if use IF EXISTS if the backend supports it
  - isDropIfExistsEnabled
```
public boolean isDropIfExistsEnabled()
```
    Description copied from interface: Backend
    
    Returns whether backend should add IF EXISTS for generated DROPs.
    
    Specified by:
    
    isDropIfExistsEnabled in interface Backend
    
    Returns:
    
    true if IF EXISTS is turned on and supported, false if not supported or turned off
  - toInternalType
```
public String toInternalType(String sqlTypeName)
```
    Description copied from interface: Backend
    
    Converts a backend specific type name to an internal name used by driver specific methods.
    
    Specified by:
    
    toInternalType in interface Backend
    
    Parameters:
    
    sqlTypeName - the original type used in SQL scripts
    
    Returns:
    
    the JDBC internal name
  - isArrayOperatorSupported
```
public boolean isArrayOperatorSupported(String operator)
```
    Description copied from interface: Backend
    
    Returns whether the backend supports given array operator.
    
    Specified by:
    
    isArrayOperatorSupported in interface Backend
    
    Parameters:
    
    operator - the array operator
    
    Returns:
    
    true if supported
  - setArray
```
public void setArray(PreparedStatement statement,
                     int pos,
                     SqlType type,
                     Collection<?> elements,
                     String operator)
              throws SQLException
```
    Description copied from interface: Backend
    
    Sets an array parameter in a prepared statement.
    
    Specified by:
    
    setArray in interface Backend
    
    Parameters:
    
    statement - the prepared statement
    
    pos - the parameter position (starting at 1)
    
    type - the element's SQL type
    
    elements - the elements to be converted to an array parameter
    
    operator - the array operator
    
    Throws:
    
    SQLException
  - sqlCreateTableIntroWithoutComment
```
protected String sqlCreateTableIntroWithoutComment(String tableName)
```
    Generates the first line of a CREATE TABLE statement.
    
    Parameters:
    
    tableName - the tablename with optional schema separated by a dot
    
    Returns:
    
    the SQL code including the opening bracket
  - createPassword
```
protected String createPassword(char[] password)
```
    Creates a password string from a password char array.
    Unfortunately, DriverManager.getConnection(String, String, String) requires the password as a string. This method creates a string from a char array and optionally decrypts it. Encrypted passwords are detected by a leading ~. If an unencrypted password must begin with a ~, a double ~~ must be used.
    
    Parameters:
    
    password - the probably encrypted password
    
    Returns:
    
    the cleartext password
  - normalizeDefault
```
protected String normalizeDefault(String str)
```
    Normalize the default string to compare.
    
    Parameters:
    
    str - the default value as a string, may be null
    
    Returns:
    
    the normalized value, never null
  - sqlCreateTableAttributeWithoutComment
```
protected String sqlCreateTableAttributeWithoutComment(String columnName,
                                                       SqlType sqlType,
                                                       int size,
                                                       int scale,
                                                       boolean nullable,
                                                       Object defaultValue,
                                                       boolean primaryKey,
                                                       boolean withTrailingComma)
```
    Generates the attribute definition of a CREATE TABLE statement.
    
    Parameters:
    
    columnName - the database column name
    
    sqlType - the JDBC sql type
    
    size - the optional size
    
    scale - the optional scale
    
    nullable - true if NULL, else NOT NULL
    
    defaultValue - the optional default value
    
    primaryKey - true if this is a primary key
    
    withTrailingComma - true if append a comma
    
    Returns:
    
    the SQL code
  - extractWhereClause
```
protected String extractWhereClause(String sql,
                                    int whereOffset)
```
    Extracts the where clause from a given sql.
    
    Parameters:
    
    sql - the sql statement
    
    whereOffset - the location of WHERE in sql
    
    Returns:
    
    the where clause without the keyword WHERE
  - isDropIfExistsSupported
```
protected boolean isDropIfExistsSupported()
```
    Adds "IF EXISTS" to drop clauses, if supported by the backend.
    Makes migration a little more robust in case the same SQL scripts are applied to different databases than those used to generate the migration scripts for.
    
    Returns:
    
    true if supported
  - isExceptionStateStartingWith
```
protected boolean isExceptionStateStartingWith(SQLException ex,
                                               String... prefixes)
```
    Checks if the exception's state starts with a given string(s).
    
    Parameters:
    
    ex - the exception
    
    prefixes - the prefixes the state starts with
    
    Returns:
    
    true if so
  - isExceptionStateMatching
```
protected boolean isExceptionStateMatching(SQLException ex,
                                           String... states)
```
    Checks if the exception's state equals given string(s).
    
    Parameters:
    
    ex - the exception
    
    states - the states to check for
    
    Returns:
    
    true if matches
  - isExceptionErrorCodeMatching
```
protected boolean isExceptionErrorCodeMatching(SQLException ex,
                                               int... codes)
```
    Checks if the exception's error code equals given number(s).
    
    Parameters:
    
    ex - the exception
    
    codes - the error codes to check for
    
    Returns:
    
    true if matches

Class AbstractBackend

Field Summary

Fields inherited from interface org.tentackle.sql.Backend

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface org.tentackle.sql.Backend

Field Detail

TYPE_BIGINT

TYPE_BIT

TYPE_BLOB

TYPE_CLOB

TYPE_BOOL

TYPE_BOOLEAN

TYPE_BYTEA

TYPE_BYTE

TYPE_CHAR_1

TYPE_DATE

TYPE_DATETIME

TYPE_DATETIME_YEAR_TO_SECOND

TYPE_DECIMAL

TYPE_DECIMAL_19

TYPE_DOUBLE

TYPE_FLOAT

TYPE_FLOAT4

TYPE_FLOAT8

TYPE_INT

TYPE_INT2

TYPE_INT4

TYPE_INT8

TYPE_INTEGER

TYPE_NCHAR_1

TYPE_NUMBER

TYPE_NUMBER_1

TYPE_NUMBER_5

TYPE_NUMBER_10

TYPE_NUMBER_19

TYPE_NVARCHAR

TYPE_NVARCHAR_MAX

TYPE_REAL

TYPE_TEXT

TYPE_TIME

TYPE_TIMESTAMP

TYPE_TINYINT

TYPE_SMALLFLOAT

TYPE_SMALLINT

TYPE_VARBINARY_MAX

TYPE_VARCHAR

Constructor Detail

AbstractBackend

Method Detail

isMatchingName

toString

createConnection

getMetaData

getTableHeaders

isTemporaryName

isReservedTableName

isReservedSchemaName

getEmptyString

sqlAsBeforeTableAlias

needAliasForSubselect

sqlRequiresExtraCommit

sqlResultSetIsClosedSupported

sqlComment

sqlJoin

sqlFunction

getCoalesceKeyword

allowsExpressionsReferringToTablesBeingUpdated

needSetLongWorkaround

needTxForFetchsize

isConstraintException

isCommunicationLinkException

isTransientTransactionException

getMaxSize

getMaxScale

getDefaultSize

getDefaultSchema

getModelMetaData

getTableMetaData