求帮助delphi中关于sql

sql.Add('selectrq,pm,gg,sum(jz) as jz from ylrkb where andpm='''+trim(ComboBox1.Text)+''' and gg='''+trim(ComboBox2.Text)+''' and rq>='''+datetostr(DateTimePicker1.date)+''' and rq<='''+datetostr(DateTimePicker2.date)+'''
and (zt<>'''+'删除'+''' or zt is null) //这样的括号应该怎样改 在sql里面可以运行，delphi中提示错误
group byrq,pm,gg ');