PDO 最后插入 ID 总是正确的吗？

Question

I have the following code:

<?
$query =$db->prepare("INSERT INTO a_table (id, a_field) VALUES ('', (:a_field)");
$query->bindParam(":a_field", $a_value);
$query->execute();
$last_id = $db->lastInsertId('a_table');
?>

What I want to ask is this. Imagine when two people load the page at exactly the same time, is it a possible danger that the other persons query is inserted before the last ID is retrieved, mixing up the IDs?

Answer 1

No, this situation is impossible. Method $db->lastInsertId() returns last inserted id for this DB conection. In other page will be another connection and another last inserted id.

Answer 2

PDO 将返回当前活动数据库连接插入的最后一个 ID。

Answer 3

Just faced following situation

Have file post.php which includes another file (like insert.php ).

Whole code to insert in mysql is located in insert.php

In insert.php is code $id_of_inserted_row = $db->lastInsertId();

Then in insert.php is echo $id_of_inserted_row; which shows correct value.

But echo $id_of_inserted_row; in post.php shows incorrect value (as i see shows 7 numbers less than actual value). I do not understand why, just need to take into account.

Update

Sorry, above written was because inserted in two tables and mistakenly used the same $id_of_inserted_row = $db->lastInsertId(); for both tables.

So i have the same conclusion as in other answers: lastInsertId() gets id of last inserted row.

Faced situation. I inserted 2 rows in mysql. In such case i see that lastInsertId() is id of the first inserted row (not the last). Do not understand why... Found answer https://stackoverflow.com/a/12574752/2118559

Important If you insert multiple rows using a single INSERT statement, LAST_INSERT_ID() returns the value generated for the first inserted row only. The reason for this is to make it possible to reproduce easily the same INSERT statement against some other server.