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如何使用MySQL分组订购但随机订购？

2024-04-28 02:26:03 553

让我们首先创建一个表-

mysql> create table DemoTable
   (
   Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   Value char(1)
   );

使用插入命令在表中插入一些记录-

mysql> insert into DemoTable(Value) values('X');

mysql> insert into DemoTable(Value) values('Y');

mysql> insert into DemoTable(Value) values('X');

mysql> insert into DemoTable(Value) values('X');

mysql> insert into DemoTable(Value) values('Y');

mysql> insert into DemoTable(Value) values('Z');

mysql> insert into DemoTable(Value) values('Z');

使用select语句显示表中的所有记录-

mysql> select *from DemoTable;

这将产生以下输出-

+----+-------+
| Id | Value |
+----+-------+
| 1  | X     |
| 2  | Y     |
| 3  | X     |
| 4  | X     |
| 5  | Y     |
| 6  | Z     |
| 7  | Z     |
+----+-------+
7 rows in set (0.00 sec)

情况1-以下是要分组但随机的查询-

mysql> select DemoTable.*
   from DemoTable join
   (
   select Value, rand() as `random_Value`
   from DemoTable
   group by Value
   ) tbl2
   on DemoTable.Value = tbl2.Value
order by tbl2.`random_Value`;

这将产生以下输出-

+----+-------+
| Id | Value |
+----+-------+
| 6  | Z     |
| 7  | Z     |
| 1  | X     |
| 3  | X     |
| 4  | X     |
| 2  | Y     |
| 5  | Y     |
+----+-------+
7 rows in set (0.00 sec)

情况2-由于我们正在显示随机记录，因此让我们再次运行上述查询以显示-

mysql> select DemoTable.*
   from DemoTable join
   (
   select Value, rand() as `random_Value`
   from DemoTable
   group by Value
   ) tbl2
   on DemoTable.Value = tbl2.Value
order by tbl2.`random_Value`;

这将产生以下输出-

+----+-------+
| Id | Value |
+----+-------+
| 2  | Y     |
| 5  | Y     |
| 6  | Z     |
| 7  | Z     |
| 1  | X     |
| 3  | X     |
| 4  | X     |
+----+-------+
7 rows in set (0.00 sec)

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如何使用MySQL分组订购但随机订购？

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