select * from client
where clientid in (select clientid from sale where paystate='已付'
and dogid in (select dogid from dog where @fieldname=1) )
where clientid in (select clientid from sale where paystate='已付'
and dogid in (select dogid from dog where @fieldname=1) )
select client.*
from client join sale on client.clientid=sale.clientid
join dog on sale.dogid=dog.dogid
where sale.paystate='已付' and dog.@fieldname=1
icevi(按钮工厂) :这两种写法的结果是一样吧!第二种写法更易看,易懂吧!给分!