根据现有字段更新列 [英] Updating column based on existing fields

问题描述

我创建了一个新字段，我需要根据现有字段进行更新.想知道MYSQL是否可以使用变量执行此操作，还是必须使用PHP?由于该表非常庞大(超过30万行，我认为通过查询本身可以做到最好)

I created a new fields and I need to update it based on existing fields. Wondering if MYSQL can do this using variables or do I have to use PHP? Since the table is huge (300k+ rows, I assume its best done with a query itself is possible)

当前:

+-----+--------+--------------+
| pid |  mfr   |     pnum     |
+-----+--------+--------------+
|     | MCAFEE | HIDYFM-AA-DA |
+-----+--------+--------------+

预期:

+-----------------------+--------+--------------+
|          pid          |  mfr   |     pnum     |
+-----------------------+--------+--------------+
| MCAFEE___HIDYFM-AA-DA | MCAFEE | HIDYFM-AA-DA |
+-----------------------+--------+--------------+

推荐答案

只需连接两个字段并设置为pid

Just concatenate the two fields and set to pid

UPDATE table_name SET pid=CONCAT(mfr,"___",pnum)

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