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