MySQL 如果重复，则仅从表中选择所有值一次
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SELECT all value from table only once if they're duplicated
提问by Vitaliy Isikov
Lets say I have a table with the following rows/values:
假设我有一个包含以下行/值的表：
+--------+----------+
| ID | adspot |
+--------+----------+
| 1 | A |
| 2 | B |
| 3 | A |
| 4 | B |
| 5 | C |
| 6 | A |
+--------+----------+
I need a way to select the values in adspot but only onceif they're duplicated. So from this example I'd want to select A once and B once. The SQL result should look like this then:
我需要一种方法来选择 adspot 中的值，但如果它们重复，则只能选择一次。所以从这个例子中，我想选择一次 A 和一次 B。SQL 结果应如下所示：
+----------+
| adspot |
+----------+
| A |
| B |
| C |
+----------+
I'm using mySQL and PHP, in case anyone asks.
我正在使用 mySQL 和 PHP，以防万一。
Thanks.
谢谢。
回答by Dre
SELECT DISTINCT adspot FROM your_table;( this may not perform well at all in large tables )
SELECT DISTINCT adspot FROM your_table;（这在大表中可能根本表现不佳）
回答by amosrivera
SELECT adspot FROM table GROUP BY adspot
