Re: Check Constraints

If you carefully check the syntax diagrams in the SQL Reference you will find that your 1st attempt was invalid. You may do either of these:

ALTER TABLE <t> ADD CONSTRAINT <name> CHECK (COMMISSION > 0)

ALTER TABLE <t> ADD CHECK (COMMISSION > 0)

But you cannot use the keyword CONSTRAINT without specifying the constraint name. By its error message, Oracle appears to believe that you are trying to add a column called "CONSTRAINT" with an inline column check constraint referencing a different column. Change "CONSTRAINT" to "FOO" and you get the same result:

SQL> ALTER TABLE EMP
2 ADD foo
3 check (SAL > 0);
check (SAL > 0)
*
ERROR at line 3:
ORA-02438: Column check constraint cannot reference other columns Received on Fri Jan 21 2005 - 09:29:36 CST