Oracle CURRVAL and NEXTVAL Pseudocoloumns

You can use CURRVAL and NEXTVAL in:

* The SELECT list of a SELECT statement that is not contained in a subquery, materialized view, or view

* The SELECT list of a subquery in an INSERT statement

* The VALUES clause of an INSERT statement

* The SET clause of an UPDATE statement

Restrictions: You cannot use CURRVAL and NEXTVAL:

* A subquery in a DELETE, SELECT, or UPDATE statement

* A query of a view or of a materialized view

* A SELECT statement with the DISTINCT operator

* A SELECT statement with a GROUP BY clause or ORDER BY clause

* A SELECT statement that is combined with another SELECT statement with the UNION, INTERSECT, or MINUS set operator

* The WHERE clause of a SELECT statement

* DEFAULT value of a column in a CREATE TABLE or ALTER TABLE statement

* The condition of a CHECK constraint

Also, within a single sql statement that uses CURRVAL or NEXTVAL, all referenced LONG columns, updated tables, and locked tables must be located on the same database.