如何修改这句SQL，急！！

[sw1018518]

select b.* from R_jobsclass a, R_jobs b where b.zt=0 and (DATEDIFF(day, b.tjsj, GETDATE()) <=30) and ((b.Jobs like '%"&JobKey&"%' or b.Adcontent like '%"&JobKey&"%') or (a.Jobsname like '%"&JobKey&"%' and a.Jobscode=b.Selectedjob)) order by b.tjsj desc

显示结果是同一信息3000多条啊，我期望的是：
如果没有符合条件b.Jobs like '%"&JobKey&"%' or b.Adcontent like '%"&JobKey&"%'的时候则选用条件a.Jobsname like '%"&JobKey&"%' and a.Jobscode=b.Selectedjob

而结果就是符合以上条件的都一起按照order by b.tjsj desc显示出来！

[ziping]

select b.* from R_jobsclass a, R_jobs b where b.zt=0 and (DATEDIFF(day, b.tjsj, GETDATE()) <=30) and ( case when (b.Jobs like '%"&JobKey&"%' or b.Adcontent like '%"&JobKey&"%') then true else (a.Jobsname like '%"&JobKey&"%' and a.Jobscode=b.Selectedjob) end) order by b.tjsj desc

用CASE吧