How to overcome a few restrictions of LONG data type (Doc ID 205288.1)

Symptoms

You try to select distinct values from a long column, create a table using as select with a long column, insert into a table by selecting the long column from another table and an ORA-00997: illegal use of LONG datatype ... occurs

It is a restriction of the long columns that they cannot be used with a DISTINCT operator and cannot be referenced when creating a table with query
(CREATE TABLE...AS SELECT...) or when inserting into a table(or view) with a query (INSERT INTO ... SELECT...).

This article gives a workaround to these restrictions using a table function in 8i and above.

This workaround is applicable if and only if your data in the long column is less than 4K. 

Changes

No relevant change to the database has been done. 

Cause