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About Table Types

The most common typc of table in an Oracle databasc is a relational table. which is structured with simple columns similar to the employees table. Two other table types

arc supported: objęci tables and XMLType tablcs. Any of the thrcc table types can be defined as permanent or tempo tary. Tcmporary tablcs hołd scssion-private data that exists only for the duration of a transaction or session. Thcy arc useful in applications where a results set must be hcld tcmporarily in mcmory, perhaps bccausc the results set is constructcd by running multiplc operations.

You can build relational tables in either heap or index-organized structures. In heap structures, the rows are not stored in any particular order. In index-organized tables, the row order is determined by the values in one or morę selected columns. For some applications, index-organized tables provide enhanced performance and morę efficient use of disk space.

This section describes permanent, heap-organized tables. For information about other table types and when to use them, see Oracle Database Administrator's Guide and Oracle

Database Concepts. For the syntax required to crcate tables with SQL, see Oracle Database SQL Language Reference.