CLOB 和 BLOB

An SQL CLOB is a built-in type that stores a Character Large Object as a column value in a row of a database table.

An SQL BLOB is a built-in type that stores a Binary Large Object as a column value in a row of a database table.

Introduction to Large Objects

https://docs.oracle.com/cd/B28359_01/appdev.111/b28393/adlob_intro.htm#ADLOB001

TO_BLOB

https://docs.oracle.com/cd/B28359_01/server.111/b28286/functions186.htm#SQLRF30029

SELECT TO_BLOB(raw_column) blob FROM raw_table;

TO_CLOB

https://docs.oracle.com/cd/B19306_01/server.102/b14200/functions182.htm

UPDATE PRINT_MEDIA 
   SET AD_FINALTEXT = TO_CLOB (AD_FLTEXTN);