如何在正负值的 select 查询中用 GROUP BY？

接下来是正负值 select 查询中 GROUP BY 的语法

select *from yourTableName group by -yourColumnName;

我们首先创建一个表

mysql> create table DemoTable (Value int);
Query OK, 0 rows affected (0.60 sec)

以下是使用 insert 命令向表中插入一些记录的查询

mysql> insert into DemoTable values(-10);
Query OK, 1 row affected (0.20 sec)
mysql> insert into DemoTable values(-20);
Query OK, 1 row affected (0.10 sec)
mysql> insert into DemoTable values(20);
Query OK, 1 row affected (0.13 sec)
mysql> insert into DemoTable values(10);
Query OK, 1 row affected (0.13 sec)
mysql> insert into DemoTable values(-10);
Query OK, 1 row affected (0.15 sec)
mysql> insert into DemoTable values(-10);
Query OK, 1 row affected (0.19 sec)
mysql> insert into DemoTable values(-20);
Query OK, 1 row affected (0.16 sec)
mysql> insert into DemoTable values(-30);
Query OK, 1 row affected (0.07 sec)
mysql> insert into DemoTable values(30);
Query OK, 1 row affected (0.12 sec)

以下是使用 select 命令在表中显示记录的查询

mysql> select *from DemoTable;

此操作将产生以下输出

+-------+
| Value |
+-------+
|   -10 |
|   -20 |
|    20 |
|    10 |
|   -10 |
|   -10 |
|   -20 |
|   -30 |
|    30 |
+-------+
9 rows in set (0.00 sec)

以下是按正负值分组的查询

mysql> select *from DemoTable group by -Value;

此操作将产生以下输出

+-------+
| Value |
+-------+
|   -10 |
|   -20 |
|    20 |
|    10 |
|   -30 |
|    30 |
+-------+
6 rows in set (0.00 sec)

Krantik Chavan

更新于: 2019 年 7 月 30 日

465 次浏览

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