我的插入击中了哪个唯一键? [英] Which unique key is hit with my insert?

问题描述

使用 MySQL，当我有一个包含(例如)三个键的表(一个主键、自动增量和列上的两个唯一键，例如代码"和名称")时，我该如何(有效地)知道在进行插入时违反了哪个唯一性约束吗?

Using MySQL, when I have a table with (for example) three keys (one primary, auto-increment, and two uniques on a column, eg. 'code' and 'name'), how can I (efficiently) know which uniqueness constraint was violated when doing an insert?

您收到错误 #1062 - 键 2 的重复条目值"，但我怎么知道键 2 是代码"列的键而不是名称"列的键?

You get an error #1062 - Duplicate entry 'Value' for key 2, but how do I know key 2 is the key for the 'code' column and not the 'name' column?

我们与多个开发人员一起开发这个应用程序，我想防止有一天我们不以相同的顺序将约束添加到表中，所以我机器上的第二个键是另一台机器上的第三个键，反之亦然-相反.

We develop this application with multiple developers, and I want to prevent the day we don't add the constraints to a table in the same order, so the second key on my machine is the third key on another machine, and vice-versa.

映射到所涉及的确切列名并不是必需的，只映射到键名就足够了.

Mapping to the exact column names involved is not really necessary, just to the key names is enough.

推荐答案

正如 Bobby 所建议的，SHOW 索引返回一个带有相关键索引的结果集，检查这个 页面 了解更多示例:

As Bobby has suggested, SHOW indexes returns a resultset with relevant key index, check this page for further examples:

SHOW INDEXES FROM products_to_categories
WHERE Key_name = "PRIMARY"
AND Seq_in_index = '2';

+------------------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| Table                  | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment |
+------------------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| products_to_categories |          0 | PRIMARY  |            2 | category_id | A         |           0 |     NULL | NULL   |      | BTREE      |         |
+------------------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+

但是，如果不超过以下解决方法，这可能需要尽可能多的代码.

However this will probably require as much code if not more than the following workaround.

检查您插入的值与表中的现有行发生冲突:

Check which value you inserted collides with an existing row in the table:

SELECT code FROM myTable WHERE code = 'the_value_you_tried_to_insert';

或

SELECT name FROM myTable WHERE name = 'the_value_you_tried_to_insert';

虽然不是一个非常优雅的解决方案.

Albeit not a very elegant solution.

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