check if entry is in database already

teejayy1013

Hey guys,

Im trying to set up username and password database and im trying to prevent people from signing up with the same username twice by querying the database "ComputerClub" and checking to see if the entered username ($Name1) is already in the database in the column "Name".

This is my script currently, but no matter what i enter, i keep getting an invalid query with the mysql error of "No database selected"...can anyone help me and tell me what im doing wrong? Thanks

if($Password!=$Password2){
			echo 'Please make sure your passwords match <br>';
			echo '<a href=member.php>Go Back</a href>';
		}else{
			mysqli_connect('database','quinntk','password', 'DBquinntk') OR die ('Could not connect to MySQL: ' . mysqli_connect_error());
			mysql_select_db("ComputerClub");
			$Name1 = $_POST['Name'];
			$result=mysql_query("SELECT Name FROM ComputerClub WHERE Name='$Name1'");
			if(!$result){
				die('Invalid Query'. mysql_error());
			}

nemonoman

My guess is that the name of the database you are attempting to select is NOT ComputerClub. Check your spelling and your cApitaLiZatioNs.

bradgrafelman

You're using the [man]MySQLi[/man] library to connect, yet then you try to use the older [man]MySQL[/man] library to select a database and execute queries. You need to pick one library or the other (preferably MySQLi).
You could get rid of the SELECT query altogether - just add a UNIQUE index on the name column. Then, you'd simply execute the INSERT query as if all is well, and if you get the MySQL error code corresponding to a duplicate key (error #1062 maybe? I don't recall for sure) you'd display whatever is necessary when they've chosen a duplicate username.
Also note that your script is vulnerable to SQL injection attacks. User-supplied data should never be placed directly into a SQL query; instead it should first be sanitized with a function such as [man]mysql_real_escape_string/man.