SElECT 'ALTER TABLE '+OBJECT_NAME(c.parent_obj)+'  DROP CONSTRAINT '+ c.name

FROM sys.sysconstraints a,sys.columns b,sys.sysobjects c

   WHERE

     a.colid = b.column_id AND a.id = b.object_id AND

    b.name in ('upc','ean','isbn') AND c.type = 'D' AND c.id = a.constid