这是一道笔试时候遇到的手写sql语句的题目：
要求：查出表中相同的机构、单位下，10,11月两个月工资总额排名第一第二的客户
源数据如下图所示：
建表语句：
CREATE TABLE `tabletest` ( `open_inst_id` varchar(20) default NULL, `Merch_id` varchar(20) default NULL, `cust_id` char(20) default NULL, `salary` int(20) default NULL, `datatime` varchar(20) default NULL) ENGINE=InnoDB DEFAULT CHARSET=utf8
插入数据：
INSERT INTO `test`.`tabletest`(`open_inst_id`,`Merch_id`,`cust_id`,`salary`,`datatime`) VALUES ( '10007331','01','001','3000','201809');
INSERT INTO `test`.`tabletest`(`open_inst_id`,`Merch_id`,`cust_id`,`salary`,`datatime`) VALUES ( '10007331','01','001','3500','201810');
INSERT INTO `test`.`tabletest`(`open_inst_id`,`Merch_id`,`cust_id`,`salary`,`datatime`) VALUES ( '10007331','01','001','3500','201811');
INSERT INTO `test`.`tabletest`(`open_inst_id`,`Merch_id`,`cust_id`,`salary`,`datatime`) VALUES ( '10007331','01','002','5000','201809');
INSERT INTO `test`.`tabletest`(`open_inst_id`,`Merch_id`,`cust_id`,`salary`,`datatime`) VALUES ( '10007331','01','002','5000','201810');
INSERT INTO `test`.`tabletest`(`open_inst_id`,`Merch_id`,`cust_id`,`salary`,`datatime`) VALUES ( '10007331','01','002','5500','201811');
INSERT INTO `test`.`tabletest`(`open_inst_id`,`Merch_id`,`cust_id`,`salary`,`datatime`) VALUES ( '10007331','01','003','4000','201809');
INSERT INTO `test`.`tabletest`(`open_inst_id`,`Merch_id`,`cust_id`,`salary`,`datatime`) VALUES ( '10007331','01','003','4000','201810');
INSERT INTO `test`.`tabletest`(`open_inst_id`,`Merch_id`,`cust_id`,`salary`,`datatime`) VALUES ( '10007331','01','003','4000','201811');
INSERT INTO `test`.`tabletest`(`open_inst_id`,`Merch_id`,`cust_id`,`salary`,`datatime`) VALUES ( '10007000','02','004','2000','201809');
INSERT INTO `test`.`tabletest`(`open_inst_id`,`Merch_id`,`cust_id`,`salary`,`datatime`) VALUES ( '10007000','02','004','2000','201810');
INSERT INTO `test`.`tabletest`(`open_inst_id`,`Merch_id`,`cust_id`,`salary`,`datatime`) VALUES ( '10007000','02','004','2000','201811');
INSERT INTO `test`.`tabletest`(`open_inst_id`,`Merch_id`,`cust_id`,`salary`,`datatime`) VALUES ( '10007000','02','005','6000','201809');
INSERT INTO `test`.`tabletest`(`open_inst_id`,`Merch_id`,`cust_id`,`salary`,`datatime`) VALUES ( '10007000','02','005','6000','201810');
INSERT INTO `test`.`tabletest`(`open_inst_id`,`Merch_id`,`cust_id`,`salary`,`datatime`) VALUES ( '10007000','02','005','6000','201811');
INSERT INTO `test`.`tabletest`(`open_inst_id`,`Merch_id`,`cust_id`,`salary`,`datatime`) VALUES ( '10007000','02','006','5000','201809');
INSERT INTO `test`.`tabletest`(`open_inst_id`,`Merch_id`,`cust_id`,`salary`,`datatime`) VALUES ( '10007000','02','006','5500','201810');
INSERT INTO `test`.`tabletest`(`open_inst_id`,`Merch_id`,`cust_id`,`salary`,`datatime`) VALUES ( '10007000','02','006','5000','201811');
实现步骤：
/**查出表中相同的机构、单位下，10,11月两个月工资总额排名第一第二的客户*/
1.筛选10.11月份的数据
SELECT open_inst_id,Merch_id,cust_id,SUM(salary)count_salary FROM tabletest WHERE datatime IN ('201810','201811') GROUP BY cust_id ORDER BY count_salary DESC
2.按部门和总薪资进行分组
SELECT * FROM
(SELECT open_inst_id,Merch_id,cust_id,SUM(salary)count_salary
FROM tabletest WHERE datatime IN ('201810','201811')
GROUP BY cust_id ORDER BY count_salary DESC LIMIT 4)m1
ORDER BY m1.Merch_id,count_salary DESC
实现结果：
