问个SQL问题
怎么统计一个分组查询后的记录总数？

比如：
select   a   from   t   group   by   a
我要知道结果返回多少条记录


我这样写：
select   count(a)   from   t   group   by   a   为啥不行？

请指点，不甚感激！


------解决方案--------------------
select a,count(a) from t group by a 为啥不行？
你前面没有a元素后面怎么group by
------解决方案--------------------
ls的正解
------解决方案--------------------
look
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declare @t table
(a int)

select a from @t group by a
select @@rowcount
------解决方案--------------------
or
----------------------

select count(a) from (select a from @t group by a) b
------解决方案--------------------
support Red_angelX
------解决方案--------------------
select a, count(a) from t group by a
------解决方案--------------------
select a, count(*) from t group by a
------解决方案--------------------
jf
------解决方案--------------------
select count(min_lvl)
from (
select min_lvl from jobs
group by min_lvl) tb
------解决方案--------------------
select count(a) from (select a from t group by a)
------解决方案--------------------
select count(1) from t group by a
------解决方案--------------------
前面没有a元素
------解决方案--------------------
比如 select a, b from t group by a 的结果如下：
a b
-------
a1 1
a2 3
a3 2

这时我要求返回记录总数，也就是3

---------

可以直接這麼寫

Select Count(Distinct a) From t