我有一个查询
select empl.idemp ,(select em.firstnm from tbl_employeemaster em where em.idemp = empl.approvedby) as approvedby from tbl_empleaveapplication empl
join tbl_employeemaster emp on empl.idemp = emp.idemp
join tbl_leavemaster lvm on empl.idleavemaster = lvm.idleavemaster
我需要使用zend db来构建这种类型的查询