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本文次要展现如何应用 mysql 的多列组合查问

何为多列组合查问呢，就是查问的值不再是单个列的值，而是组合列的值。比方 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 查问

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 = 查问

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

多列组合查问平时比拟少见，首次看还感觉挺神奇的。

doc

• mysql-filtering-by-multiple-columns
• selecting-where-two-columns-are-in-a-set