Starts a transaction and specifies its characteristics. A
transaction is a group of statements whose changes can be made
permanent or undone only as a unit.
A transaction ends with a COMMIT or ROLLBACK statement. If you
end the transaction with the COMMIT statement, all the changes
made to the database by the statements are made permanent. If you
end the transaction with the ROLLBACK statement, the statements
do not take effect.
You must end the transaction with a COMMIT or ROLLBACK statement
before starting or declaring another transaction. If you try to
start or declare a transaction while another one is active, SQL
generates an error message.
Besides the SET TRANSACTION statement, you can specify the
characteristics of a transaction in one of two other ways:
o If you specify the DECLARE TRANSACTION statement, the
declarations in the statement take effect when SQL starts a
new transaction that is not started by the SET TRANSACTION
statement. SQL starts a new transaction with the first
executable data manipulation or data definition statement
following the DECLARE TRANSACTION, COMMIT, or ROLLBACK
statement.
o If you omit both the DECLARE and SET TRANSACTION statements,
SQL automatically starts a transaction (using the read/write
option) with the first executable data manipulation or data
definition statement following a COMMIT or ROLLBACK statement.
Thus, you can retrieve and update data without declaring or
setting a transaction explicitly.
See the Oracle Rdb SQL Reference Manual for examples of when you
would want to use the DECLARE TRANSACTION statement instead of
the SET TRANSACTION statement.
You can specify many options with the SET TRANSACTION statement,
including:
o Transaction mode (READ ONLY/READ WRITE)
o Lock specification clause (RESERVING options)
o Horizontal partition specification (RESERVING options)
o Wait mode (WAIT/NOWAIT)
o Isolation level
o Constraint evaluation specification clause
o Multiple sets of all the preceding options for each database
involved in the transaction (ON . . . AND ON)
The Arguments section explains these options in more detail.
Additional Information:
explode
extract