Is there a way to test if the LOB data associated with the OCILobLocator() is NULL before performing an OCILobRead() or OCILobGetLength()?
No. The only way to find out if the LOB data has a length of 0 is by calling OCILobGetLength(). If the LOB is NULL, then the LOB column stores NULL and there is no LOB locator nor is there a LOB. Therefore, a SQL select of a NULL LOB returns NULL instead of a LOB locator. If the LOB exists, the LOB locator is stored in the LOB column and the LOB data length can range anywhere from 0 to 4 GB. A SQL SELECT of a LOB with a length of 0 returns a valid LOB locator that can be passed to OCILobGetLength(). In order to create a LOB with a length of 0, you can issue a SQL INSERT statement passing EMPTY_BLOB() or EMPTY_CLOB() for the internal LOB column.
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