Where子句的M​​ySQL语法

Question

Im not good in php. I have a web application that displays the Data from my MySQL Database. I am not getting any erros but I need to fetch the Data I want.

ex. code.

<?php
$dbhost = 'localhost';
$dbuser = 'user';
$dbpass = 'password';
$conn = mysql_connect($dbhost, $dbuser, $dbpass);
$token = $_GET['token'];

if(! $conn )
  {
    die('Could not connect: ' . mysql_error());
  }
$sql = "SELECT * FROM table WHERE token = '" . $token . "'";

mysql_select_db('database');
$retval = mysql_query( $sql, $conn );
if(! $retval )
  {
    die('Could not get data: ' . mysql_error());
  }

 while($row = mysql_fetch_array($retval, MYSQL_ASSOC))
   {
     //Displays the data
   echo "The Token is here";
   }

  mysql_close($conn);
  ?>

I have no errors in here. But I need to do something like, If the token data is not yet added to the table, then I will put an echo message like.. "The token is not yet added here". Where I can put the syntax here? Please help me. I am new in php.

Answer 1

Use this:

 if(mysql_num_rows($retval)) {
     while($row = mysql_fetch_array($retval, MYSQL_ASSOC))
     {
      //Displays the data
      echo "The Token is here";
     }
   } else {
     echo "The token is not yet added here";
   }

Answer 2

Try with mysql_num_rows like

$sql = "SELECT * FROM table WHERE token = '" . $token . "'";
mysql_select_db('database');
$retval = mysql_query( $sql, $conn );
$num_rows = mysql_num_rows($retval);
if($num_rows < 1) {
    echo "The token is not yet added here";
} else {
    echo "Token already added";
}

And try to avoid using mysql_* functions due to they are deprecated.Instead use mysqli_* functions or PDO statements.

Answer 3

Put condition with mysql_num_rows(). If that value is 0 then you can show the message The token is not yet added here else some other codes.

Answer 4

Try if the following way:

if(isset($_GET['token']))
{
if(! $conn )
  {
    die('Could not connect: ' . mysql_error());
  }
$sql = "SELECT * FROM table WHERE token = '" . $_GET['token'] . "'";

mysql_select_db('database');
$retval = mysql_query( $sql, $conn );
if(! $retval )
  {
    die('Could not get data: ' . mysql_error());
  }

 while($row = mysql_fetch_array($retval, MYSQL_ASSOC))
   {
     //Displays the data
   echo "The Token is here";
   }

  mysql_close($conn);
}
else
{
   echo "The token is not yet added here";
}