Re: Checking for table existence

On Fri, Sep 14, 2001 at 06:58:29PM +0000, Julester wrote:
> 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.
You can have psql output its internal queries and that will give you
some insight:

roberto@brasileiro:~/documents/pictures$ psql -e foobar
Welcome to psql, the PostgreSQL interactive terminal.
...
foobar=# \d blah
********* QUERY *********
SELECT relhasindex, relkind, relchecks, reltriggers, relhasrules
FROM pg_class WHERE relname='blah'
*************************

********* QUERY *********
SELECT a.attname, format_type(a.atttypid, a.atttypmod), a.attnotnull,
a.atthasdef, a.attnum
FROM pg_class c, pg_attribute a
WHERE c.relname = 'blah' AND a.attnum > 0 AND a.attrelid = c.oid
ORDER BY a.attnum
*************************

********* QUERY *********
SELECT substring(d.adsrc for 128) FROM pg_attrdef d, pg_class c
WHERE c.relname = 'blah' AND c.oid = d.adrelid AND d.adnum = 1
*************************
                    Table "blah"Attribute |           Type           |   Modifier    
-----------+--------------------------+---------------something | timestamp with time zone | default 'now'name      |
character(50)
-Roberto
-- 
+------------| Roberto Mello - http://www.brasileiro.net |------------+
Computer Science, Utah State University  -    http://www.usu.edu
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