序
本文主要展示如何使用mysql的多列組合查詢
何為多列組合查詢呢，就是查詢的值不再是單個列的值，而是組合列的值。比如where (column1,column2) in ((a1,b1),(a2,b2),(a3,b3))
例項
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查詢
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=查詢
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小結
多列組合查詢平常比較少見，初次看還覺得挺神奇的。