sqlite老是报错no such column解决方法

sqlite老是报错no such column
SELECT qsmallClass.Sname, qproducts.pmodel, qproducts.punit, qmaintain.mcount FROM qsmallClass INNER JOIN (qproducts INNER JOIN qmaintain ON qproducts.pid = qmaintain.pid) ON qsmallClass.Sid = qproducts.Sid

报错 no such column: qproducts.pmodel

请问这是怎么回事,要如何解决?

------解决方案--------------------
SELECT a.Sname, b.pmodel, b.punit, c.mcount FROM qsmallClass a
 INNER JOIN qproducts b ON a.Sid = b.Sid
 INNER JOIN qmaintain c ON b.pid = c.pid
去掉（）