本文介绍了MySQL 合并两列并添加到一个新列中的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着跟版网的小编来一起学习吧！
问题描述
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我的 MySQL 表具有以下结构:
I have the following structure with a MySQL table:
+----------------+----------------+----------+
| zipcode | city | state |
+----------------+----------------+----------+
| 10954 | Nanuet | NY |
+----------------+----------------+----------+
我想将上述 3 列合并为一列，如下所示:
I want to combine the above 3 columns into one column like this:
+---------------------+
| combined |
+---------------------+
| 10954 - Nanuet, NY |
+---------------------+
并且我想在不破坏原始 3 个字段的情况下将此组合"列添加到表的末尾.
And I want to add this "combined" column to the end of the table without destroying the original 3 fields.
推荐答案
创建列:
ALTER TABLE yourtable ADD COLUMN combined VARCHAR(50);
更新当前值:
UPDATE yourtable SET combined = CONCAT(zipcode, ' - ', city, ', ', state);
自动更新所有未来值:
CREATE TRIGGER insert_trigger
BEFORE INSERT ON yourtable
FOR EACH ROW
SET new.combined = CONCAT(new.zipcode, ' - ', new.city, ', ', new.state);
CREATE TRIGGER update_trigger
BEFORE UPDATE ON yourtable
FOR EACH ROW
SET new.combined = CONCAT(new.zipcode, ' - ', new.city, ', ', new.state);
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