EMPTY_CLOB return an empty LOB locator that can be used to initialize a LOB variable or, in an
UPDATE statement, to initialize a LOB column or attribute to
EMPTY means that the LOB is initialized, but not populated with data.
An empty LOB is not the same as a null LOB, and an empty
CLOB is not the same as a LOB containing a string of 0 length. For more information, see Oracle Database SecureFiles and Large Objects Developer's Guide.
Appendix C in Oracle Database Globalization Support Guide for the collation derivation rules, which define the collation assigned to the return value of
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
UPDATE print_media SET ad_photo = EMPTY_BLOB();