From: | "Josh Berkus" <josh(at)agliodbs(dot)com> |
---|---|
To: | "Julester" <cubalibr(at)optonline(dot)net> |
Cc: | pgsql-sql(at)postgresql(dot)org |
Subject: | Re: Checking for table existence |
Date: | 2001-09-18 03:54:23 |
Message-ID: | web-120865@davinci.ethosmedia.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-sql |
Julester,
> Hi everyone. In my old SQL Server days, I used a command such as "IF
> exists(select name from sys_objects where name = 'xyztable')" to
> check if a
> table existed before creating it with a standard CREATE command. I
> looked
> in the PostgreSQL documentation, but for the life of me, I can't find
> an
> equivalent. I can view if the table exists by doing a select against
> the
> meta-data tables, but what about the IF statement ? Any help would
> be
> greatly appreciated. Thanks.
<grin> You've gotten a lot of complex answers to a simple question.
Confused yet?
If you're doing this in PL/pgSQL, you want a couple of functions:
(Hey Roberto, how about posting the 1st function on your site?)
CREATE FUNCTON table_exists(
VARCHAR ) RETURNS BOOLEAN AS '
DECLARE
t_name ALIAS for $1;
t_result VARCHAR;
BEGIN
--find table, case-insensitive
SELECT relname INTO t_result
FROM pg_class
WHERE relname ~* (''^'' || t_name || ''$'')
AND relkind = 'r';
IF t_result IS NULL THEN
RETURN FALSE;
ELSE
RETURN TRUE;
END IF;
END;'
LANGUAGE 'plpgsql';
... then you build your function around this:
CREATE FUNCTION my_function ( ...
...
IF NOT table_exists(''my_table'') THEN
CREATE TABLE ...
END IF;
...
Got the idea?
-Josh
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