你能相信mysql_insert_id吗？ [英] Can you trust mysql_insert_id?

问题描述

我有一个注册页面，然后将数据插入MySQL的两个表中。第一个是技术信息，如用户名/密码/电子邮件，另一个是个人信息，如姓名/地址等。

I have a registration page which then inserts data into two tables in MySQL. The first one is technical information like username/password/email, and the other one is for personal information like name/address and such.

我的技术信息表有一个主要信息键自动增量ID，然后，一旦我在此表中创建行，我立即在具有相同ID的常规信息表中创建另一行。

My technical information table has a primary key auto incremental ID, and then, once I create the row in this table, I immediately create another row in the general information table with the same id.

要获取该ID，我在第一次插入查询后立即使用 mysql_insert_id（）函数。

To obtain that ID, I use the mysql_insert_id() function right after the first insert query.

我的问题相当笼统：你真的相信这个函数它必然会返回相应的索引吗？如果我的网站有很多用户注册怎么办？每一秒，它仍然可靠，并始终返回ID？或者它只返回生成的表的最后一个主键？

My question is rather general: can you really trust this function that it will necessarily return the appropriate index? What if I had a website with many users registering every second, would it still be reliable, and always return the ID? Or does it just return the last primary key of a table generated?

推荐答案

是的，你可以。

该函数是每个会话，但它也只对最后一个查询有效。

The function is per-session, but it is also only valid for the very last query.

也就是说，你永远不会让一个用户污染另一个的last_insert_id，但是你无法从两次插入前恢复insert_id。当您需要连续执行多个插入并且之后不需要ID时，请将它们设置为变量：

That is, you'll never have one user "polluting" the last_insert_id of another, but you cannot recover an insert_id from two inserts ago. When you need to do several inserts in a row and don't need the ids until later, set them as variables:

INSERT INTO ...
SET @foo_id = LAST_INSERT_ID();
INSERT INTO ...
SET @bar_id = LAST_INSERT_ID();
INSERT INTO some_join_table VALUES (@foo_id, @bar_id);

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