[Resolved] Check for unique on register

AndrewWest

I know how to do error checking on a query, but if the query tries to insert something and it's not uniqe it doesn't error out..

1) Why doesn't it error out like it should

2) How do I check for a unique field..

In this case my uniqe field is name (for unique usernames?)

$query = "INSERT INTO members (name, password, email, register_ip)
VALUES ('$username', '$password', '$email', '$register_ip')";
mysql_query($query);

$self = $_SERVER['php_self'];

if (!$query) {
   die('Invalid query: ' . mysql_error());
} else {
echo "<div align='center'>Your registration was submitted! Please <a href='$self?page=login'>Login</a></div><br><br>";
}

drew010

there is nothing about a database that says you cant have 2 identical pieces of data. if this were the case, two people couldn't share the same zipcode, or even have the same name for that matter.
if you want to check for a unique username, you need to do a select statement yourself checking to see if that username already is in the database and if it is, dont insert it and tell the user they need to choose another one.


$q = "SELECT * FROM members WHERE username = '$username'";
$r = mysql_query($q);

if (mysql_num_rows($r)) { //username exists
  echo "That username already exists.  Please choose another.";
  //form here
} else { //doesnt exist
  $q = "INSERT INTO.......";
  //...
}

AndrewWest

Actually if you set a column to unique it will not insert it if there is alreay one one. Although as you said it won't tell you that it's not inserting..

But definately thanks what you posted is exactly what I was looking for. 🙂