To: pgsql-admin@postgresql.org
From: Thomas Kellerer <spam_eater@gmx.net>
Subject: Re: Is it possible to create a CHECK constraint for my use case?
Date: Tue, 31 Jan 2012 09:33:19 +0100
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Gnanakumar, 31.01.2012 09:11:
> Hi,
>
> Our Production server is running PostgreSQL v8.2.22 on CentOS5.2.

You know that 8.2 is "end-of-live"?
http://www.postgresql.org/support/versioning/


> There are 2 columns in the table: "managertype" numeric(1) and "managerid"
> numeric(10).  "managertype" accepts only 2 valid values, either '1' or '2'.
>
> managertype  |	managerid
> ---------------------------------
>          1           |  null values NOT allowed
>          2           | null values allowed
> ---------------------------------
>
> We want to enable a CHECK constraint based on 2 columns data in the table in
> such a way that if "managertype" is 1, then null values are not allowed in
> "managerid" column.  In other words, I want to create a CHECK constraint
> something like this: IF (managertype = 1) THEN managerid IS NOT NULL.
>
> Is it possible to create a CHECK constraint for my use case explained above?


Something like this:

check ( (managertype = 2) or (managertype = 1 and managerid is not null) )

Not sure if the condition (managertype = 2) is actually needed, if the managertype is already constrained to 1/2 but I can't test it right now.

Thomas