Read all constraint for the current database

select db_name() as CONSTRAINT_CATALOG
,t_obj.name as TABLE_NAME
,user_name(c_obj.uid) as CONSTRAINT_SCHEMA
,c_obj.name as CONSTRAINT_NAME
,col.name as COLUMN_NAME
,col.colid as ORDINAL_POSITION
,com.text as DEFAULT_CLAUSE

from sysobjects c_obj
join syscomments com on c_obj.id = com.id
join sysobjects t_obj on c_obj.parent_obj = t_obj.id 
join    sysconstraints con on c_obj.id = con.constid
join syscolumns col on t_obj.id = col.id
and con.colid = col.colid
where
c_obj.uid = user_id()
and c_obj.xtype = 'D'