一个关于 SQL 统计的问题，求解
SELECT YEAR(ins.CREATETIME) AS CYEAR,MONTH(ins.CREATETIME) AS CMONTH, COUNT(ins.ID) AS C
FROM WfInstance ins inner join WfModel mo
ON ins.ModelID = mo.ID
WHERE Status IN(2,3,4,9) AND SYSTEMTYPE=1
GROUP BY YEAR(ins.CREATETIME),MONTH(ins.CREATETIME)
这个语句查出三个列 ： 年，月，4状态总数
目标：我想查出四个列： 年，月，4状态总数，3状态总数(包括 3,4,9三个状态 ）
不知道能不能在这一个语句里完成？
望大侠们出招儿，谢过！ sql
[解决办法]
SELECT YEAR(ins.CREATETIME) AS CYEAR,MONTH(ins.CREATETIME) AS CMONTH, COUNT(ins.ID) AS C
, sum(case when Status IN(3,4,9) then 1 else 0 end) AS C1
FROM WfInstance ins inner join WfModel mo
ON ins.ModelID = mo.ID
WHERE Status IN(2,3,4,9) AND SYSTEMTYPE=1
GROUP BY YEAR(ins.CREATETIME),MONTH(ins.CREATETIME)
