Обсуждение: Is it possible to create a CHECK constraint for my use case?

Hi,

Our Production server is running PostgreSQL v8.2.22 on CentOS5.2.  We want
to enable a specific CHECK constraint for our application table as explained
below:

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?

Regards,
Gnanam

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'ttest it right now. 

Thomas

On Tue, 31 Jan 2012 13:41:00 +0530, Gnanakumar wrote:

> Hi,
>
> Our Production server is running PostgreSQL v8.2.22 on CentOS5.2.  We
> want to enable a specific CHECK constraint for our application table as
> explained below:
>
> 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?

Production server? Bollocks. It's homework. Look it up.