3 replies to this topic

[hetra]

Hello all,

I'm making a registration page for my website. I need to check if a username already exists. What SQL syntax and/or function can do this?

[WingedPanther]

It really depends on how you're storing them, currently.

I usually do something like: SELECT COUNT(*) AS MYCOUNTER FROM USERS WHERE USER_NAME='new name';

0 means it's available, 1 means it isn't.

Other people will do a select * and look to see if records were returned

Some people do an insert and handle the duplicate value if a primary key violation occurs.

[Alexander]

It should be simple as selecting the count, i.e.

SELECT COUNT(username) FROM tbl_users WHERE username = 'John'

If count > 0:
   //User already exists

You could probably use mysql_num_rows without COUNT if you are using PHP if you require more information (i.e. exists, and was registered at a date, rather than just exists already)

[yassinebelkaid]

You can do something like this : SELECT username FROM tlb_name WHERE username = '".$username."', then use mysql_num_rows($query). then do a condition if the row equals 1, it means the username exists, if not it will continue and store the new username.