mysql 數據操作 單表查詢 group by 練習
阿新 • • 發佈:2019-03-13
per style spa 平均薪資 bold 以及 數據 薪資 ros
小練習:
1. 查詢崗位名以及崗位包含的所有員工名字
mysql> select post,group_concat(name) from employee group by post ; +-----------+-------------------------------------------------+ | post | group_concat(name) | +-----------+-------------------------------------------------+ |operation | 程咬鐵,程咬銅,程咬銀,程咬金,張野 | | sale | 格格,星星,丁丁,丫丫,歪歪 | | teacher | 成龍,jinxin,jingliyang,liwenzhou,yuanhao,alex | +-----------+-------------------------------------------------+ 3 rows in set (0.00 sec)
2. 查詢崗位名以及各崗位內包含的員工個數
mysql> selectpost,count(id) from employee group by post ; +-----------+-----------+ | post | count(id) | +-----------+-----------+ | operation | 5 | | sale | 5 | | teacher | 6 | +-----------+-----------+ 3 rows in set (0.00 sec)
3. 查詢公司內男員工和女員工的個數
mysql> selectsex,count(id) from employee group by sex ; +--------+-----------+ | sex | count(id) | +--------+-----------+ | male | 8 | | female | 8 | +--------+-----------+ 2 rows in set (0.00 sec)
4. 查詢崗位名以及各崗位的平均薪資
mysql> select post,avg(salary) from employee group by post ; +-----------+---------------+ | post | avg(salary) | +-----------+---------------+ | operation | 16800.026000 | | sale | 2600.294000 | | teacher | 175766.718333 | +-----------+---------------+ 3 rows in set (0.00 sec)
5. 查詢崗位名以及各崗位的最高薪資
mysql> select post,max(salary) from employee group by post ; +-----------+-------------+ | post | max(salary) | +-----------+-------------+ | operation | 20000.00 | | sale | 4000.33 | | teacher | 1000000.31 | +-----------+-------------+ 3 rows in set (0.10 sec)
6. 查詢崗位名以及各崗位的最低薪資
mysql> select post,min(salary) from employee group by post ; +-----------+-------------+ | post | min(salary) | +-----------+-------------+ | operation | 10000.13 | | sale | 1000.37 | | teacher | 2100.00 | +-----------+-------------+ 3 rows in set (0.00 sec)
7. 查詢男員工與男員工的平均薪資,女員工與女員工的平均薪資
mysql> select sex,avg(salary) from employee group by sex ; +--------+---------------+ | sex | avg(salary) | +--------+---------------+ | male | 136700.055000 | | female | 7250.183750 | +--------+---------------+ 2 rows in set (0.01 sec)
mysql 數據操作 單表查詢 group by 練習