Обсуждение: Re: Daily Digest V1 #377

>
> I'm writing a very robust validation script in perl for database entry. One
> of the things I'd like to do is check how large a field is, and make sure
> that the entry into that field isn't too big. Problem is, for variable length
> fields, DBD::Pg returns a -1 size, using the pg_size attribute.
>
> Is there something I am missing? Is there a way to get the size of variable
> length types using DBI/DBD::Pg, in particular, char() and varchar()?
>

Try this SQL (replace the 'table_name' and 'attribute_name').  This should give you the length of your varchar().

SELECT a.atttypmod-4 as length
FROM pg_class c, pg_attribute a, pg_type t
WHERE c.relname = 'table_name'
  AND a.attname = 'attribute_name'
  AND a.attnum > 0
  AND a.attrelid = c.oid
  AND a.atttypid = t.oid;

LM.Liu