Thread: Built-in functions - does an obect exist...

In many other db systems you can use built in functions to check to see if
an object exists in the db...

For example, in Sybase, you can use the object_id function to check to see
if an object exists...
  if object_id('some table, view, stored procedure, etc. name') is not null
     -- perform some action, like drop a stored proc
  else
     -- perform some other action
  End -- if


Does an equivalent function exist in Postgres?
Furthermore, where should I look to find the list of such built-in
functions?

On Tue, Jun 08, 2004 at 14:08:11 -0500,
  "Loftis, Charles E" <charles.loftis@eds.com> wrote:
> In many other db systems you can use built in functions to check to see if
> an object exists in the db...
>
> For example, in Sybase, you can use the object_id function to check to see
> if an object exists...
>   if object_id('some table, view, stored procedure, etc. name') is not null
>      -- perform some action, like drop a stored proc
>   else
>      -- perform some other action
>   End -- if
>
>
> Does an equivalent function exist in Postgres?
> Furthermore, where should I look to find the list of such built-in
> functions?

The system catalog and the information schema have metadata about objects.
You can query those tables to find out if an object with a particular name
currently exists. The logic for what to do depending on what is found
will probably need to be in your application or in a function. Straight
SQL is pretty limited for providing conditional code execution.