mysql：多表，union，count，group by的问题，求教

Question

select A.uid,count(*) from A GROUP by A.uid UNION all 
select A.uid,count(*) from A,B where B.neid = A.neid GROUP by A.uid UNION all 
select A.uid,count(*) from A,C where C.Type = 'student' and C.neid=A.neid GROUP by A.uid；

如果用每行语句单独查询，结果分别是这样的