Locking Tables

[dwilson]

can anyone please explain how locking tables work. I have a update page that a users clicks on and asks for a request number, when they click submit it takes them to a form where they fill in all the info that they want to update. Once they are done they click submit and it calls another page that does all the updating process. I want to be able to lock the table so only one user can update the table at one time. Basically if a user is on the update page I dont want another user to be able to access or update the same page until the first user is done.

Where do I put the lock table command and unlock command. Can I start the lock on my first page(where they enter a number) and issue a unlock table on the last page(processing page). Please can someone help me

[nemonoman]

Typically, one locks tables just before an insert or update.

1. Lock Tables

2. SELECT info to see if the form data is still valid
   (?? has some else entered a similar record, or updated the record since the form was being filled out)

3. If all is OK:
   INSERT or UPDATE

Else
some error message to the user that his info isn't going to fly.

4. Unlock Tables

The idea of Locking Tables for the duration of a form being filled out is a Bad Idea. The person filling out the form might need to go to the bathroom, only to have a heart attack on the toilet, and his heirs might never come back to unlock the tables.