EMPTY_CLOB is an advanced function that the Oracle database supports. It is used to initialize a LOB column to EMPTY in an INSERT or UPDATE statement. It can also be used to initialize a LOB variable. The EMPTY_CLOB function is supported in the various versions of the Oracle/PLSQL, including, Oracle 12c, Oracle 11g, Oracle 10g, Oracle 9i and Oracle 8i.
UPDATE students SET student_marks = EMPTY_CLOB();
Here, the student_marks column would be initialized to EMPTY.