Thread: Help with displaying data types.

I am trying to perform a query that will:

1. Return all user defined attributes from a relation.

2. Also return the datatypes of each relation.

So far I can only achieve part 1 with the following:

select attname from pg_class,pg_attribute
where relname=relation_name and
attrelid = pg_class.oid and
atttypid != 26 and
atttypid != 27 and
atttypid != 28 and
atttypid != 29;

But what do I need to add to return the datatype of each attribute. Any 
suggestions please?

Regards,

Rob.
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"Rob Burne" <robburne@hotmail.com> writes:
> I am trying to perform a query that will:
> 1. Return all user defined attributes from a relation.
> 2. Also return the datatypes of each relation.

> So far I can only achieve part 1 with the following:

> select attname from pg_class,pg_attribute
> where relname=relation_name and
> attrelid = pg_class.oid and
> atttypid != 26 and
> atttypid != 27 and
> atttypid != 28 and
> atttypid != 29;

That's a bad way to do it, because your query will drop user-defined
columns of type OID (among others).  I'd suggest testing for attnum > 0
to get rid of system columns.

> But what do I need to add to return the datatype of each attribute. Any 
> suggestions please?

Join against pg_type.  For example,

select attname, typname
from pg_class c, pg_attribute a, pg_type t
where relname = relation_name and
attrelid = c.oid and
atttypid = t.oid and
attnum > 0
order by attnum;

psql does a lot of these sorts of queries for its \d features.
Try starting psql with -E so you can see what queries it issues
when you do a \d ...
        regards, tom lane