mysql - CONCAT列并将其复制到另一个表MySQL

我要做的是通过obj_id将一些列复制到其他表中

UPDATE obj_object
INNER JOIN obj_extract as address ON (obj_object.id = address.obj_id AND address.category_id = 1)
INNER JOIN obj_extract as city ON (obj_object.id = city.obj_id AND city.category_id = 2)
INNER JOIN obj_extract as country ON (obj_object.id = country.obj_id AND country.category_id = 3)
INNER JOIN obj_extract as phone ON (obj_object.id = phone.obj_id AND phone.category_id = 4)
SET obj_object.address = address.info,
    obj_object.city = city.info,
    obj_object.country = country.info,
    obj_object.phone = phone.info

但有些obj_extract行有相同的category_id，如果包含相同obj_id的记录有多个具有相同category_id的行，则需要计数如果有，则需要concat这些条目并复制到obj_object表列。表格示例：

+----+--------------+---------+---------+
| ID |  category_id |  info   | obj_id  |
+----+--------------+---------+---------+
|  1 |        1     |   test  |    2    |
+----+--------------+---------+---------+
|  2 |        1     |  test1  |    2    |
+----+--------------+---------+---------+
|  3 |        2     |   test2 |    2    |
+----+--------------+---------+---------+

我想说：

 obj_object.address = 'test - test1', // // value from address.info
 obj_object.city = 'test2', // value from city.info

最佳答案

您需要考虑使用GROUP_CONCAT：

UPDATE obj_object o
SET o.address = (SELECT GROUP_CONCAT(info)
                FROM obj_extract o2
                WHERE o.id = o2.obj_id AND o2.category_id = 1),
   o.city = (SELECT GROUP_CONCAT(info)
            FROM obj_extract o3
            WHERE o.id = o3.obj_id AND o3.category_id = 2),
   o.country = (SELECT GROUP_CONCAT(info)
               FROM obj_extract o4
               WHERE o.id = o4.obj_id AND o4.category_id = 3),
   o.phone = (SELECT GROUP_CONCAT(info)
             FROM obj_extract o5
             WHERE o.id = o5.obj_id AND o5.category_id = 4)

祝你好运。

关于mysql - CONCAT列并将其复制到另一个表MySQL，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/14688514/