Vert.x Common SQL interface
The common SQL interface is used to interact with Vert.x SQL services.
You obtain a connection to the database via the service interface for the specific SQL service that you are using (e.g. JDBC/MySQL/PostgreSQL).
The SQL Connection
A connection to the database is represented by SQLConnection
.
Auto-commit
When you obtain a connection auto commit is set to true
. This means that each operation you perform will effectively
execute in its own transaction.
If you wish to perform multiple operations in a single transaction you should set auto commit to false with
setAutoCommit
.
When the operation is complete, the handler will be called:
connection.set_auto_commit(false) { |res,res_err|
if (res_err == nil)
# OK!
else
# Failed!
end
}
Executing queries
To execute a query use query
The query string is raw SQL that is passed through without changes to the actual database.
The handler will be called with the results, represented by ResultSet
when the query has
been run.
connection.query("SELECT ID, FNAME, LNAME, SHOE_SIZE from PEOPLE") { |res,res_err|
if (res_err == nil)
# Get the result set
resultSet = res
else
# Failed!
end
}
The ResultSet
instance represents the results of a query.
The list of column names are available with getColumnNames
, and the actual results
available with getResults
The results are a list of JsonArray
instances, one for each row of the results.
columnNames = resultSet['columnNames']
results = resultSet['results']
results.each do |row|
id = row[0]
fName = row[1]
lName = row[2]
shoeSize = row[3]
end
You can also retrieve the rows as a list of Json object instances with getRows
-
this can give you a somewhat simpler API to work with, but please be aware that SQL results can contain duplicate
column names - if that’s the case you should use getResults
instead.
Here’s an example of iterating through the results as Json object instances:
rows = resultSet['rows']
rows.each do |row|
id = row["ID"]
fName = row["FNAME"]
lName = row["LNAME"]
shoeSize = row["SHOE_SIZE"]
end
Prepared statement queries
To execute a prepared statement query you can use
queryWithParams
.
This takes the query, containing the parameter place holders, and a JsonArray
or parameter
values.
query = "SELECT ID, FNAME, LNAME, SHOE_SIZE from PEOPLE WHERE LNAME=? AND SHOE_SIZE > ?"
params = [
"Fox",
9
]
connection.query_with_params(query, params) { |res,res_err|
if (res_err == nil)
# Get the result set
resultSet = res
else
# Failed!
end
}
Executing INSERT, UPDATE or DELETE
To execute an operation which updates the database use update
.
The update string is raw SQL that is passed through without changes to the actual database.
The handler will be called with the results, represented by UpdateResult
when the update has
been run.
The update result holds the number of rows updated with getUpdated
, and
if the update generated keys, they are available with getKeys
.
columnNames = resultSet['columnNames']
results = resultSet['results']
results.each do |row|
id = row[0]
fName = row[1]
lName = row[2]
shoeSize = row[3]
end
Prepared statement updates
To execute a prepared statement update you can use
updateWithParams
.
This takes the update, containing the parameter place holders, and a JsonArray
or parameter
values.
update = "UPDATE PEOPLE SET SHOE_SIZE = 10 WHERE LNAME=?"
params = [
"Fox"
]
connection.update_with_params(update, params) { |res,res_err|
if (res_err == nil)
updateResult = res
puts "No. of rows updated: #{updateResult['updated']}"
else
# Failed!
end
}
Executing other operations
To execute any other database operation, e.g. a CREATE TABLE
you can use
execute
.
The string is passed through without changes to the actual database. The handler is called when the operation is complete
sql = "CREATE TABLE PEOPLE (ID int generated by default as identity (start with 1 increment by 1) not null,FNAME varchar(255), LNAME varchar(255), SHOE_SIZE int);"
connection.execute(sql) { |execute,execute_err|
if (execute_err == nil)
puts "Table created !"
else
# Failed!
end
}
Using transactions
To use transactions first set auto-commit to false with setAutoCommit
.
You then do your transactional operations and when you want to commit or rollback use
commit
or
rollback
.
Once the commit/rollback is complete the handler will be called and the next transaction will be automatically started.
# Do stuff with connection - updates etc
# Now commit
connection.commit() { |res,res_err|
if (res_err == nil)
# Committed OK!
else
# Failed!
end
}
Closing connections
When you’ve done with the connection you should return it to the pool with close
.