php / mysql - need to find out id of last inserted row

[Chronicle]

hi
how can ifind out the last id (or last value for the primary key in a table) for a query i just entered?
i want to do something like:
insert into reviews (id', 'intro') values (null, '$intro' etc)

then something like:
insert into games ('id', 'reviewid') values (null, '$idfrompreviousquery')

(i know those queries are not correct, just to give a basic idea)

cheers

 

[Goksly]

http://www.php.net/manual/en/function.mysql-insert-id.php

HTH.

 

[Nate]

I do it this way

$new_sql = "select MAX(id) from reviews";
$get_new_sql= mysql_query($new_sql) or die(mysql_error());
$new_id = mysql_result($get_new_sql,"id");

that is how i would do it anyway

 

[toString]

But is Goksly better in that it uses one query?

 

[Nate]

the way i did it only queires once, but i suppose Goksly is better.

my way works for me just thought i would share how i do it

 

[Beansprout]

I do it this way

$new_sql = "select MAX(id) from reviews";
$get_new_sql= mysql_query($new_sql) or die(mysql_error());
$new_id = mysql_result($get_new_sql,"id");

that is how i would do it anyway

Look into "race conditions"

 

[toString]

Sorry, what I meant was you still have to do the insert query and then the select max query.
Whereas the other way you just do the insert.


Edit, and I guess beansprout is saying that inbetween the 2 queries someone else may have jumped in and inserted another record - thus returning the wrong record in the select max query... Possible, I guess!

 

[Beansprout]

Edit, and I guess beansprout is saying that inbetween the 2 queries someone else may have jumped in and inserted another record - thus returning the wrong record in the select max query... Possible, I guess!

Correct, and very possible

 

[Nate]

that is a very good point and something i never really thought about. I guess i have always thought that it is execusted quick enough to not cause a problem.

Thank you for pointing that out!

 

[Goksly]

selecting the max id with a reviewer name (assuming they have to have one) will stop that error being possible -> unless the guy has a split personality

 

[Dj_Jestar]

dual sessions is not eliminated by that process.

It's also less efficient than using mysql_insert_id() which is there for this exact purpose, so using anything else is just plain.. silly.