time lag between data retrieval and updating record.

[Anonymous]

Howdy, I haven't looked over previous posts, so sorry if someone has asked something similar:

I use php and I have a script to pull in a record and then lock it after it is pulled in. The problem I have is very rarely someone will access the page at the same time and since the script first grabs a record, and then in the next step or two it updates/locks the record, there is a lag that the script can actually give two or more people the same record. I am using a character field to flag if the student is 'locked' or not.

Is there a way to grab a record and update it in the same step, or a function similar to mysql_insert_id to grab the record that was last updated. IF there was a function like this, then I could just lock a record, and then grab the data in the next step.

-- Also, I just thought that I might be able to have each instance of the script have a unique id set to some variable. Then see if it is possible to update one row with a field containing this key, and then in the next step it would grab the data with the key. Such as:
$key = something;
update table set field=$key where locked=no limit 1;
select * from table where field=$key;

I'm not sure if I can put a limit 1 in my update, but I will look into it. I just throught I would throw this up on the board to see if anyone has any good suggestions.

Thanks

 

[Anonymous]

It looks like the update clause has the LIMIT key word, so if that works how I think it will, that should allow me to update one record and then use the key to retrieve the data after I update it. ...problem solved.