如何在正負值的 select 查詢中用 GROUP BY？

接下來是正負值 select 查詢中 GROUP BY 的語法

select *from yourTableName group by -yourColumnName;

我們首先建立一個表

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記錄的查詢

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 命令在表中顯示記錄的查詢

mysql> select *from DemoTable;

此操作將產生以下輸出

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

以下是按正負值分組的查詢

mysql> select *from DemoTable group by -Value;

此操作將產生以下輸出

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

Krantik Chavan

更新於: 2019 年 7 月 30 日

465 次瀏覽

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