PK columns

How to get the list of columns which compose the PK on a table? I want to get it from system tables.
Thanks.select c.name
from
sysindexkeys k join syscolumns c
on k.id = c.id
and k.colid = c.colid
where
k.id = object_id('MyTableName')
and k.indid=1
order by k.keyno

or, simplier:

select col_name(id,colid)
from sysindexkeys
where id = object_id('A3') and indid=1 order by keyno|||Thanks. But I need to get the Primary key columns not clustered index keys. I think for indid = 1 means cluatered key, but it may not be the primary key.|||If @.tblname is null it gives the information about all the tables. If not, set it to a specific table.

declare @.tblname varchar(100)
set @.tblname = NULL
SELECT TOP 100 PERCENT WITH TIES
tc.TABLE_NAME
, kcu.COLUMN_NAME
, kcu.ORDINAL_POSITION -- Position in the key
, c.DATA_TYPE
, c.CHARACTER_MAXIMUM_LENGTH
, c.CHARACTER_SET_NAME -- typically iso_1 or Unicode
, c.COLLATION_NAME -- Case/Accent Sensitivity etc.
, c.NUMERIC_PRECISION -- Digits of data
, c.NUMERIC_SCALE -- places to right of decimal
, c.DATETIME_PRECISION
FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS tc
INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE kcu
ON tc.TABLE_CATALOG = kcu.TABLE_CATALOG
AND tc.TABLE_SCHEMA = kcu.TABLE_SCHEMA
AND tc.TABLE_NAME = kcu.TABLE_NAME
AND tc.CONSTRAINT_NAME = kcu.CONSTRAINT_NAME
INNER JOIN INFORMATION_SCHEMA.[COLUMNS] c
ON tc.TABLE_CATALOG = c.TABLE_CATALOG
AND tc.TABLE_SCHEMA = c.TABLE_SCHEMA
AND tc.TABLE_NAME = c.TABLE_NAME
AND kcu.COLUMN_NAME= c.COLUMN_NAME
WHERE tc.CONSTRAINT_TYPE = 'PRIMARY KEY'
AND (@.tblname is NULL
OR tc.TABLE_NAME = @.tblname)
AND tc.TABLE_NAME != 'dtproperties'
ORDER BY tc.TABLE_NAME
, kcu.ORDINAL_POSITION
GO