Temporary Tables

Creation Of Temporary Tables
The data in a temporary table is private for the session that created it and can be session-specific or transaction-specific. If the data is to deleted at the end of the transaction the table should be defined as follows:
CREATE GLOBAL TEMPORARY TABLE my_temp_table ( column1 NUMBER, column2 NUMBER) ON COMMIT DELETE ROWS;
If on the other hand that data should be preserved until the session ends it should be defined as follows:
CREATE GLOBAL TEMPORARY TABLE my_temp_table ( column1 NUMBER, column2 NUMBER) ON COMMIT PRESERVE ROWS;