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在MySQL中有LIMIT的多个WHERE？

2024-05-01 08:10:03 386

为此，您可以使用UNIONALL运算符。让我们首先创建一个表-

mysql> create table DemoTable
   -> (
   -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   -> Subject varchar(100)
   -> );

使用插入命令在表中插入一些记录-

mysql> insert into DemoTable(Subject) values('MySQL');

mysql> insert into DemoTable(Subject) values('MySQL');

mysql> insert into DemoTable(Subject) values('MongoDB');

mysql> insert into DemoTable(Subject) values('MongoDB');

mysql> insert into DemoTable(Subject) values('MySQL');

mysql> insert into DemoTable(Subject) values('Java');

mysql> insert into DemoTable(Subject) values('MySQL');

mysql> insert into DemoTable(Subject) values('MongoDB');

使用select语句显示表中的所有记录-

mysql> select *from DemoTable;

输出结果

+----+---------+
| Id | Subject |
+----+---------+
| 1  | MySQL   |
| 2  | MySQL   |
| 3  | MongoDB |
| 4  | MongoDB |
| 5  | MySQL   |
| 6  | Java    |
| 7  | MySQL   |
| 8  | MongoDB |
+----+---------+
8 rows in set (0.00 sec)

以下是在MySQL中使用LIMIT实现多个WHERE的查询-

mysql> (select *from DemoTable where Subject='MySQL' limit 3)
   -> union all
   -> (select *from DemoTable where Subject='MongoDB' limit 5)
   -> ;

输出结果

+----+---------+
| Id | Subject |
+----+---------+
| 1  | MySQL   |
| 2  | MySQL   |
| 5  | MySQL   |
| 3  | MongoDB |
| 4  | MongoDB |
| 8  | MongoDB |
+----+---------+
6 rows in set (0.00 sec)

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在MySQL中有LIMIT的多个WHERE？

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