Re: Checking for table existence

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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