Re: Finding the primary key of tables

2010/8/3 George Silva <georger.silva@gmail.com>:

> I'm going for Merlin's solution. Its the easiest one :P
>
> But I'm also having a problem:
>
> SELECT column_name FROM information_schema.key_column_usage k
>     LEFT OUTER JOIN information_schema.table_constraints ON (k.table_name =
> table_constraints.table_name)
> WHERE
>         table_constraints.constraint_type = 'PRIMARY KEY'
>         AND k.table_name = 'acidentes'
>         AND k.table_schema = 'public'
>
> this still returns me multiple columns. Did I forgot something?

yup -- you are supposed be matching on constraint_name, not just
table_name. try:

 SELECT column_name FROM information_schema.key_column_usage k

    LEFT OUTER JOIN information_schema.table_constraints USING
(table_schema, table_name, constraint_name)

 WHERE
        table_constraints.constraint_type = 'PRIMARY KEY'
        AND k.table_name = 'acidentes'
        AND k.table_schema = 'public'

merlin