Checking to see of a field is unique on save

[aheuermann]

I have a custom field that must be unique. I am confused to where I should add the checking code. I am using the accounts module.

If there is an extension file for this let me know because I would like my improvements not to be overwritten on upgrades.

Also is it possible to make it blink and show the error message on attempt of a save like it does when a required field is blank.
Any help would be greatly appreciated.
Thank you in advance!!

[aheuermann]

I have a custom field that must be unique. I am confused to where I should add the checking code. I am using the accounts module.

If there is an extension file for this let me know because I would like my improvements not to be overwritten on upgrades.

Also is it possible to make it blink and show the error message on attempt of a save like it does when a required field is blank.
Any help would be greatly appreciated.
Thank you in advance!!

has anyoone tried this??