TO_CLOB is one of the vital Conversion functions of Oracle. It is used to convert a LOB value to the database character set from the national character set. The TO_CLOB function is supported in the various versions of the Oracle/PLSQL, including, Oracle 12c, Oracle 11g, Oracle 10g and Oracle 9i.
TO_CLOB ( expression)
expression: It is used to specify the expression to be converted.
select TO_CLOB (clob_column) from students;
Here, the value in the field called clob_column will be converted to a CLOB value.