EMPTY_BLOB, EMPTY_CLOB
Description of the illustration empty_LOB.gif
EMPTY_BLOB and EMPTY_CLOB return an empty LOB locator that can be used to initialize a LOB variable or, in an INSERT or UPDATE statement, to initialize a LOB column or attribute to EMPTY. EMPTY means that the LOB is initialized, but not populated with data.
Restriction on LOB Locators You cannot use the locator returned from this function as a parameter to the DBMS_LOB package or the OCI.
The following example initializes the ad_photo column of the sample pm.print_media table to EMPTY:
UPDATE print_media SET ad_photo = EMPTY_BLOB();