Performing Transactions - MySQL - page 576

except mysql . connector . Error as e :
print ( "Transaction failed, rolling back. Error was:" )
print ( e )
try : # empty exception handler in case rollback fails
conn . rollback ()
except :
pass
17.8. Using Transactions in Java Programs
Problem
You want to perform a transaction in a JDBC application.
Solution
Use the standard JDBC transaction support mechanism.
Discussion
To perform transactions in Java, use your Connection object to turn off auto-commit
mode. Then, after executing your statements, use the object's commit() method to com‐
mit the transaction or rollback() to cancel it. Typically, you execute the statements for
the transaction in a try block, with commit() at the end of the block. To handle failures,
invoke rollback() in the corresponding exception handler:
try
{
conn . setAutoCommit ( false );
Statement s = conn . createStatement ();
// move some money from one person to the other
s . executeUpdate ( "UPDATE money SET amt = amt - 6 WHERE name = 'Eve'" );
s . executeUpdate ( "UPDATE money SET amt = amt + 6 WHERE name = 'Ida'" );
s . close ();
conn . commit ();
conn . setAutoCommit ( true );
}
catch ( SQLException e )
{
System . err . println ( "Transaction failed, rolling back. Error was:" );
Cookbook . printErrorMessage ( e );
// empty exception handler in case rollback fails
try
{
conn . rollback ();
conn . setAutoCommit ( true );
}
catch ( Exception e2 ) { }
}