El Mar 28 Sep 2004 11:02, T E Schmitz escribi�:
> Hello,
>
> Is it possible to set up a table CHECK, which ensures that column A is
> NOT NULL if column B = 'x' ?
CONSTRAINT constraint_name ]
CHECK (expression)
CHECK (expression)
The CHECK clause specifies an expression producing a Boolean result which new
or updated rows must satisfy for an insert or update operation to succeed. A
check constraint specified as a column constraint should reference that
column's value only, while an expression appearing in a table constraint may
reference multiple columns.
So I would say that it should be:
CONSTRAINT somename CHECK (B <> 'x' OR A IS NOT NULL)
(use a logical table to build the correct logical expression)
--
11:05:01 up 16 days, 1:23, 4 users, load average: 1.26, 0.70, 1.04
-----------------------------------------------------------------
Mart�n Marqu�s | select 'mmarques' || '@' || 'unl.edu.ar'
Centro de Telematica | DBA, Programador, Administrador
Universidad Nacional
del Litoral
-----------------------------------------------------------------
---------------------------(end of broadcast)---------------------------
TIP 2: you can get off all lists at once with the unregister command
(send "unregister YourEmailAddressHere" to [EMAIL PROTECTED])
