SELECT GoodID,sum(if(Level = 1, 1, 0)) as Better,sum(if(Level = 0, 1, 0)) as Nomal,sum(if(Level = -1, 1, 0)) as Bad from evaluates GROUP BY GoodID;
MySQL查询某个字段为某值的次数统计SQL语句
原文：http://www.cnblogs.com/yesicoo/p/4726526.html
