序
本文主要展示如何使用mysql的多列组合查询
何为多列组合查询呢，就是查询的值不再是单个列的值，而是组合列的值。比如where (column1,column2) in ((a1,b1),(a2,b2),(a3,b3))
实例
建表
create table t_demo(
id int NOT NULL AUTO_INCREMENT PRIMARY KEY,
name varchar(10),
score int
);
insert into t_demo(name,score) values('a',10);
insert into t_demo(name,score) values('b',20);
insert into t_demo(name,score) values('c',30);
insert into t_demo(name,score) values('d',40);
insert into t_demo(name,score) values('d',50);
insert into t_demo(name,score) values('e',60);
多列in查询
select * from t_demo where (name,score) in (('c',30),('e',60));
+----+------+-------+
| id | name | score |
+----+------+-------+
| 3 | c | 30 |
| 6 | e | 60 |
+----+------+-------+
2 rows in set
Time: 0.112s
多列=查询
select * from t_demo where (name,score) = ('c',30) or (name,score) = ('e',60);
+----+------+-------+
| id | name | score |
+----+------+-------+
| 3 | c | 30 |
| 6 | e | 60 |
+----+------+-------+
2 rows in set
Time: 0.119s
小结
多列组合查询平常比较少见，初次看还觉得挺神奇的。
