mysql 面试题

1. 题目： 给出表1，要得到表2的内容

       表1：    表2： 

1. 答案：

   SELECT  deptName, COUNT(gender = 1) AS '男',
   COUNT(gender = 2) AS '女' 
   FROM dept
   GROUP BY deptName 
   

    

2. 索引

   CREATE INDEX idx_temp ON dept(deptName,gender)