前言:
当前看官们对“mysqlsumdouble”大约比较重视,我们都想要分析一些“mysqlsumdouble”的相关文章。那么小编同时在网上网罗了一些关于“mysqlsumdouble””的相关内容,希望我们能喜欢,同学们快快来了解一下吧!分组统计在日常工作中经常用到,今天分享使用sum,if进行分组统计。
IF表达式:
IF(expr1,expr2,expr3)
如果 expr1 是TRUE,则返回值是expr2; 否则返回值是expr3。
查询每个部门男生、女生分别多少人?
selectdept_id,count(*) as total_num,sum(if(sex=1,1,0)) as female_num,sum(if(sex=0,1,0)) as male_num,sum(if((sex<>1 and sex<>0) or sex is null,1,0)) as unknown_numfrom staff group by dept_id;+---------+-----------+------------+----------+-------------+| dept_id | total_num | female_num | male_num | unknown_num |+---------+-----------+------------+----------+-------------+| 101 | 5 | 2 | 2 | 1 || 102 | 3 | 1 | 1 | 1 || 103 | 1 | 1 | 0 | 0 || 104 | 1 | 0 | 1 | 0 |+---------+-----------+------------+----------+-------------+4 rows in set (0.00 sec)
表结构如下:
CREATE TABLE `staff` ( `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT 'ID', `name` varchar(50) NOT NULL COMMENT '姓名', `dept_id` varchar(10) DEFAULT NULL COMMENT '部门id', `salary` double DEFAULT NULL COMMENT '工资', `sex` int(11) DEFAULT NULL COMMENT '性别,1是男生,0是女生', `created_time` datetime DEFAULT NULL COMMENT '创建时间', `updated_time` datetime DEFAULT NULL COMMENT '更新时间', PRIMARY KEY (`id`)) ENGINE=InnoDB AUTO_INCREMENT=11 DEFAULT CHARSET=utf8 COMMENT='职员表'
现有记录:
mysql> select * from staff ;+----+-------+---------+--------+------+---------------------+---------------------+| id | name | dept_id | salary | sex | created_time | updated_time |+----+-------+---------+--------+------+---------------------+---------------------+| 1 | Tom | 101 | 2500 | 1 | 2020-03-08 18:37:55 | 2020-03-08 18:37:55 || 2 | Tonny | 101 | 3500 | 1 | 2020-03-08 18:37:55 | 2020-03-08 18:37:55 || 3 | Bob | 101 | 3500 | 0 | 2020-03-08 18:37:55 | 2020-03-08 18:37:55 || 4 | Rob | 101 | 4500 | NULL | 2020-03-08 18:37:55 | 2020-03-08 18:37:55 || 5 | Sudey | 101 | 5500 | 0 | 2020-03-08 18:37:55 | 2020-03-08 18:37:55 || 6 | Sunny | 102 | 5500 | 1 | 2020-03-08 18:37:55 | 2020-03-08 18:37:55 || 7 | Sedey | 102 | 3500 | 0 | 2020-03-08 18:37:55 | 2020-03-08 18:37:55 || 8 | Bobby | 102 | 4500 | NULL | 2020-03-08 18:37:55 | 2020-03-08 18:37:55 || 9 | Weedy | 103 | 4500 | 1 | 2020-03-08 18:37:55 | 2020-03-08 18:37:55 || 10 | Jimme | 104 | 5500 | 0 | 2020-03-08 18:37:55 | 2020-03-08 18:37:55 |+----+-------+---------+--------+------+---------------------+---------------------+10 rows in set (0.00 sec)
当然也可以使用case when实现,详见:
MySQL分组统计你会吗?case when,sum,count会用吗?
MySQL,case when你真的会用吗?附避坑指南
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