Mysql的列修改成行并显示数据的简单实现

数据运维 2023-04-27 捡田螺的小男孩手机阅读

创建测试表： DROP TABLE IF EXISTS test;CREATE TABLE test (year int(11) DEFAULT NULL,month int(11) DEFAULT NULL,amount double DEFAULT NULL) ENGINE=InnoDB DEFAULT CHARSET=utf8; 插入数据： INSERT INTO test VALUES ('1991'

创建测试表：

DROP TABLE IF EXISTS test; CREATE TABLE test ( year int(11) DEFAULT NULL, month int(11) DEFAULT NULL, amount double DEFAULT NULL ) ENGINE=InnoDB DEFAULT CHARSET=utf8;

插入数据：

INSERT INTO test VALUES ('1991', '1', '1.1'); INSERT INTO test VALUES ('1991', '2', '1.2'); INSERT INTO test VALUES ('1991', '3', '1.3'); INSERT INTO test VALUES ('1991', '4', '1.4'); INSERT INTO test VALUES ('1992', '1', '2.1'); INSERT INTO test VALUES ('1992', '2', '2.2'); INSERT INTO test VALUES ('1992', '3', '2.3'); INSERT INTO test VALUES ('1992', '4', '2.3');

看到题目要求，仔细想想可以：

利用SUM(IF()) 生成列 + WITH ROLLUP 生成汇总行,并利用 IFNULL将汇总行标题显示为 Total_num

实现

SQL代码块如下：

select year, sum(if(month=1,amount,0)) as "M1", sum(if(month=2,amount,0)) as "M2", sum(if(month=3,amount,0)) as "M3", sum(if(month=4,amount,0)) as "M4" from test GROUP by year;

效果如下：