Обсуждение: check table existence...

am  Mon, dem 15.01.2007, um 13:18:11 +0100 mailte Moritz Bayer folgendes:
> Dear list,
>
> I would like to create a function which gets a tablename and checks if the
> specific table exists.The return value should be a bool.
> Now I'm wondering how to do this the best way.
>
> Any suggestions?

You can ask pg_tables:

select count(1) from pg_tables where tablename = 'foo' and schemaname = 'public';


This ask for a table called 'foo' in the schema 'public'.


Andreas
--
Andreas Kretschmer
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A. Kretschmer wrote:
> am  Mon, dem 15.01.2007, um 13:18:11 +0100 mailte Moritz Bayer folgendes:
>> Dear list,
>>
>> I would like to create a function which gets a tablename and checks if the
>> specific table exists.The return value should be a bool.
>> Now I'm wondering how to do this the best way.
>>
>> Any suggestions?
>
> You can ask pg_tables:
>
> select count(1) from pg_tables where tablename = 'foo' and schemaname = 'public';
>
>
> This ask for a table called 'foo' in the schema 'public'.

If you do (something like) that in pl/pgsql, you could RETURN FOUND
after performing that query.

--
Alban Hertroys
alban@magproductions.nl

magproductions b.v.

T: ++31(0)534346874
F: ++31(0)534346876
M:
I: www.magproductions.nl
A: Postbus 416
   7500 AK Enschede

// Integrate Your World //

Something like this will help you......

=======================

CREATE OR REPLACE FUNCTION public.check_table(varchar, varchar)
RETURNS boolean AS $$
 DECLARE
   v_cnt integer;
   v_tbl boolean;
 BEGIN
   SELECT count(1) INTO v_cnt FROM pg_tables where tablename = $1 and schemaname = $2;

    IF v_cnt > 0 THEN
     v_tbl = 'true';
    END IF;

    IF v_cnt = 0 THEN
     v_tbl = 'false';
    END IF;
return v_tbl;
END;
  $$ LANGUAGE 'plpgsql'

=========================

select check_table('emp', 'public');

-----------------------
Shoaib Mir
EnterpriseDB ( www.enterprisedb.com)

Shoaib Mir wrote:
> Something like this will help you......

Or shorter:

> =======================
>
> CREATE OR REPLACE FUNCTION public.check_table(varchar, varchar)
> RETURNS boolean AS $$
> DECLARE
>   v_cnt integer;
>   v_tbl boolean;
> BEGIN

   PERFORM 1 FROM pg_tables where tablename = $1 and

> schemaname = $2;

   RETURN FOUND;

> END;
>  $$ LANGUAGE 'plpgsql'

I'm pretty sure that should work.

--
Alban Hertroys
alban@magproductions.nl

magproductions b.v.

T: ++31(0)534346874
F: ++31(0)534346876
M:
I: www.magproductions.nl
A: Postbus 416
   7500 AK Enschede

// Integrate Your World //