sql语句case when会报case关键字的错误

Question

select * from shrzl a inner join
(select max(shrdh) shrdh,max(id) id from sfglb group by fhrdh)b on a.shrdh=b.shrdh
case when b.shrdh is not null then a.no=-1 end

Answer 1

 select a.*,
case when b.shrdh is not null then -1 else a.no end ano from shrzl a inner join 
(select max(shrdh) shrdh,max(id) id from sfglb group by fhrdh)b on a.shrdh=b.shrdh