SQL: how to find if a table exists?

From: Lee Kindness <lkindness(at)csl(dot)co(dot)uk>
To: Jean-Christian Imbeault <totsubo2001(at)netscape(dot)net>
Cc: Lee Kindness <lkindness(at)csl(dot)co(dot)uk>, pgsql-general(at)postgresql(dot)org
Subject: SQL: how to find if a table exists?
Date: 2002-09-09 14:41:54
Message-ID: 15740.45874.945784.646631@kelvin.csl.co.uk
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Look into the pg_class system table for a matching 'relame', the code
below can be installed as a plpgsql function to add a 'table_exists()'
function which returns boolean:

CREATE OR REPLACE FUNCTION table_exists(NAME) RETURNS BOOLEAN AS '
DECLARE
tab ALIAS FOR $1;
rec RECORD;
BEGIN
SELECT INTO rec *
FROM pg_class c
WHERE c.relname = tab;
IF NOT FOUND THEN
RETURN false;
ELSE
RETURN true;
END IF;
END;
' LANGUAGE 'plpgsql';

This actually matches index names too, but works for my uses... This
system table is documented at:

http://www.postgresql.org/idocs/index.php?catalog-pg-class.html

Lee.

Jean-Christian Imbeault writes:
> I need to programmatically create a table if it does not already exists.
>
> Is there an SQL statement that will allow me to query a DB to see if a
> table exists?

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