Get the default values of table columns in Postgres?

Question

I\'m looking for a way to run a query to find the default values of the columns of a table in Postgres. For example, if I made a table with the following query:

Answer 1

I'm spending some time trying to get to grips with the pg_catalog tables. I'm assuming the names and such come back from the days when letters had to be carved individually and were, consequently, very expensive ;-) Anyway, that's all a fact of life. I wanted to get the default value for a column and ran into this thread. I saw a mention of wanting to have Erwin Brandstetter's code as a function. I've wrapped it up and figured I'd add it to the archives:

CREATE OR REPLACE FUNCTION data.column_default (qualified_name text, column_name text)
  RETURNS text
 AS $$

SELECT d.adsrc AS default_value -- A human-readable representation of the default value, already typed as text.
FROM   pg_catalog.pg_attribute a
LEFT   JOIN pg_catalog.pg_attrdef d ON (a.attrelid, a.attnum)
                                     = (d.adrelid,  d.adnum)
WHERE  NOT a.attisdropped   -- no dropped (dead) columns
AND    a.attnum > 0         -- no system columns
AND    a.attrelid = qualified_name::regclass
AND    a.attname = column_name;

$$ LANGUAGE sql;

ALTER FUNCTION data.column_default (qualified_name text, column_name text) OWNER TO user_bender;

I'm using the code (probably in an inhumane manner) like so:

select pg_class.relnamespace::regnamespace as schema_name,
        attrelid::regclass as parent_name,
        attname,
       format_type(atttypid, atttypmod) as data_type,
       column_default(attrelid::regclass::text,attname),
       attnum

 from pg_attribute
 left join pg_class on (pg_class.oid = pg_attribute.attrelid::regclass)

From here I figure I'll write a view, etc., once I know better what I'm really after. For now, I'm using a CTE as a temporary view:

with attributes as
(select pg_class.relnamespace::regnamespace as schema_name,
        attrelid::regclass as parent_name,
        attname,
       format_type(atttypid, atttypmod) as data_type,
       column_default(attrelid::regclass::text,attname),
       attnum

 from pg_attribute
 left join pg_class on (pg_class.oid = pg_attribute.attrelid::regclass)
)

select *
  from attributes
 where parent_name::text = 'sales'

Corrections, improvements, and suggestions all welcome...I'm just getting my feet wet in pg_catalog.