Preventing multiple-sign up

[terryds]

Please tell me how to prevent the user from multiple sign upI am i don't want there are the same usernames...Please tell me how to do that, so the id and the username are unique...

[justsomeguy]

Check if it exists in the database before adding it.

[terryds]

I'm surprised with that answer... I see that many many web applications don't allow the user to make another account with the same name....Can you tell me how to do that?

[Don E]

For instance, you can check if the users' email address is already in the database table... if it is that means that particular user is already signed up.

[terryds]

Solved! I found this myself... Use 'Unique' !

ADD UNIQUE 'column'

Edited June 7, 2013 by terryds

[justsomeguy]

You can make it a unique index, but that's just going to cause a database error when you try to add a duplicate row. If you don't want your script to fail with a database error then do what everyone else does and check if a record already exists before adding the new one. Then you can give your own error message to the user instead of your script just failing.