LAST_INSERT_ID() to link on double table insert

Question

I run on PHP / MySql with PDO .

Let's say I have a query like this. $OrderId is auto-increment in "Orders" table. I can use LAST_INSERT_ID() to insert $OrderId in both "Orders" and "BoughtItems" tables.

INSERT INTO Orders (OrderId, CustomerName, CustomerEmail, OrderTotal, OrderTaxes)  
SET @order_id = LAST_INSERT_ID();
INSERT INTO boughtItems (OrderId,ProductId,OrderedQty) Values (@order_id, :productid_1,
:name_1),(@order_id, :productid_2, :name_2),(@order_id, :productid_3, :name_3)

What will happen if two people execute this script for different orders at the very same time ?

Any danger that they both get the same $OrderId and mix up their orders ?

Thank you for your time !

Answer 1

LAST_INSERT_ID() is calculated on a per-connection basis, so it is safe from race conditions across connections.

Therefore, if someone on a different connection to the server also performs an INSERT , it will not affect your LAST_INSERT_ID() correctness and therefore you will experience no problem.

• Reference: http://kera.name/articles/2011/08/one-less-bug-to-worry-about/