CODEWITHSUNDEEP
phpmysqlhtml
user1287949
user1287949

Reputation: 36

PHP User already exist check

$sql = 'SELECT * FROM tbluser, tblfile WHERE tbluser.Username = "'.$user.'"'; 
if ($result = mysql_query($sql)) {
if(mysql_num_rows($result)) {
    echo'User already exists';
    exit;
}
else
{
mysql_query('INSERT INTO tbluser
(`Username`, Password, BossID) VALUES  ( "'.$user.'","'.$passwd.'","'.$boss.'")')or die(mysql_error());


$sqlq = 'SELECT * FROM tbluser, tblfile WHERE tbluser.Username = "'.$user.'"'; 
$res = mysql_query($sqlq);
while($row = mysql_fetch_array($res)){
mysql_query('INSERT INTO tbluser_file
(`FileID`, UserID) VALUES  ( "'.$row['FileID'].'","'.$row['UserID'].'")')or die(mysql_error());
}
echo "Admin Added!";

}
}

I would like to check if a user already exists in my database. If he exists I want to exit, if he doesn't exist, i would like to execute above code (under the ELSE statement)

thanks in advance

Upvotes: 0

Views: 2195

Answers (3)

user1283565
user1283565

Reputation: 31

$sql = 'SELECT COUNT(*) as COUNTUSER FROM tbluser, tblfile WHERE tbluser.Username = "'.$user.'"';
while ($myRow= mysql_fetch_array($sql)) { 
    $counterUser=$myRow[COUNTUSER]; 
}
if ($counterUser>0)
{
    echo 'User already exists';
    exit;
}

Upvotes: 0

VolkerK
VolkerK

Reputation: 96159

If you create a unique index for the column Username an insert with the same value for Username as an other record already in the table will cause a specfic error code. Your script can simply try to insert the new record and handle the specific error code, something like

define('ER_DUP_KEY', 1022);

// pre-condition: $user, $passwd, $boss have been prepared for usage within an sql statement
$query = sprintf("
    INSERT INTO
        tbluser
        (`Username`, `Password`, `BossID`)
    VALUES 
        ('%s', '%s', '%s')
", $user, $passwd, $boss);

if ( !mysql_query($query) ) {
    switch(mysql_errno()) {
        case ER_DUP_KEY:
          // handle duplicate user name
          break;
        default:
          // handle other errors
    }
}

If you would use two queries (SELECT+INSERT) you had to handle race conditions, e.g. by locking the table.

edit: I missed the implicit join FROM tbluser, tblfile.
In that case you might be interested in INSERT ... ON DUPLICATE KEY UPDATE, esp. the

If a table contains an AUTO_INCREMENT column and INSERT ... UPDATE inserts a row, the LAST_INSERT_ID() function returns the AUTO_INCREMENT value. If the statement updates a row instead, LAST_INSERT_ID() is not meaningful. However, you can work around this by using LAST_INSERT_ID(expr). Suppose that id is the AUTO_INCREMENT column. To make LAST_INSERT_ID() meaningful for updates, insert rows as follows:
part. I.e.:

  • create a unique index for Username
  • do the INSERT INTO tbluser query with an ON DUPLICATE KEY UPDATE clause using LAST_INSERT_ID(expr)
  • fetch the insert id, see http://docs.php.net/function.mysql-insert-id
  • do the second insert using the insert_id from the previsous query

Upvotes: 1

user319198
user319198

Reputation:

Try below:

Make sure query is returning rows or it's ok.

change if(mysql_num_rows($result)) to if(mysql_num_rows($result) > 0) 

$sql = 'SELECT * FROM tbluser, tblfile WHERE tbluser.Username = "'.$user.'"'; 
if ($result = mysql_query($sql)) {
if(mysql_num_rows($result) > 0) {
    echo'User already exists';
    exit;
}

Upvotes: 0

Related Questions