The TO_CLOB function in Oracle SQL / PLSQL is used to convert a LOB value from national character set to database character set.
Syntax for the TO_CLOB function in Oracle SQL / PLSQL is:
SELECT TO_CLOB(expression_1)
FROM table_name;
expression_1 can be CHAR, VARCHAR2, NCHAR, NVARCHAR2, CLOB, NCLOB or LOB_COLUMN
Examples:
SELECT TO_CLOB(employee_name) FROM employee;