declare	@TableName varchar(128)
	select @TableName = 'mytbl'
	
	select 	c.COLUMN_NAME 
	from 	INFORMATION_SCHEMA.TABLE_CONSTRAINTS pk ,
		INFORMATION_SCHEMA.KEY_COLUMN_USAGE c
	where 	pk.TABLE_NAME = @TableName
	and	CONSTRAINT_TYPE = 'PRIMARY KEY'
	and	c.TABLE_NAME = pk.TABLE_NAME
	and	c.CONSTRAINT_NAME = pk.CONSTRAINT_NAME