使用同一表中另一行的数据更新行 [英] Update row with data from another row in the same table

问题描述

我有一张看起来像这样的桌子

I've got a table which looks something like this

ID   |   NAME    |  VALUE  |
----------------------------
 1   |   Test    |  VALUE1 |
 2   |   Test2   |  VALUE2 |
 1   |   Test2   |         |
 4   |   Test    |         |
 1   |   Test3   |  VALUE3 |

我正在寻找一种方法，以使用"VALUE"列中具有相同"NAME"名称的其他行中的数据更新值"Test2"和"Test"(此处ID并非唯一，复合键ID和NAME中的一行使行唯一).例如，我要查找的输出是:

I'm looking for a way to update the values 'Test2' and 'Test' with the data from other rows in the 'VALUE' column with the same 'NAME' (The ID is not unique here, a composite key of the ID and NAME make a row unique). For example, the output I'm looking for is:

ID   |   NAME    |  VALUE  |
----------------------------
 1   |   Test    |  VALUE1 |
 2   |   Test2   |  VALUE2 |
 1   |   Test2   |  VALUE2 |
 4   |   Test    |  VALUE1 |
 1   |   Test3   |  VALUE3 |

如果它在另一个表中，我会没事的，但是我对于如何使用相同的NAME值引用当前表中的另一行感到困惑.

If it was in another table I'd be fine, but I'm at a loss as to how I can reference a different row within the current table with the same NAME value.

更新

修改完manji查询后，下面是我用于有效解决方案的查询.谢谢大家！

After modifying manji query, below is the query I used for a working solution. Thanks all!

UPDATE data_table dt1, data_table dt2 
SET dt1.VALUE = dt2.VALUE 
WHERE dt1.NAME = dt2.NAME AND dt1.VALUE = '' AND dt2.VALUE != '' 

推荐答案

尝试一下:

UPDATE data_table t, (SELECT DISTINCT ID, NAME, VALUE
                        FROM data_table
                       WHERE VALUE IS NOT NULL AND VALUE != '') t1
   SET t.VALUE = t1.VALUE
 WHERE t.ID = t1.ID
   AND t.NAME = t1.NAME

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