mysqli_query没有显示任何结果

Question

I want to retrieve data matching a specific email from a MySQL table. There are 2 records associated with this email, but nothing is printed on my screen.

<?php

$conn = mysqli_connect('localhost', 'root', '', 'testdrive');


$sql = mysqli_query($conn, 
        'SELECT * FROM products_bought
        where email = "'.mysqli_real_escape_string($conn, "a@gmail.com").'"'
    );
while($row = mysqli_fetch_array($sql)){
    $fullname = $row['fullname'];
    ?>
    <p><?php echo $fullname; ?></p>
    <?php
}

?>

Answer 1

Here:

<p><?php $fullname; ?></p>

This is not actually outputting a value, you can either use echo to output the value of the variable, or use PHP short tags like so,

<p><?= $fullname; ?></p>

Or the long way using echo

<p><?php echo $fullname; ?></p>

Answer 2

To Check that you are connected to DB or not please try below code and test, also check that are you getting data in mysqli_fetch_array($sql) using print_r

    <?php

    $conn = mysqli_connect('localhost', 'root', '', 'testdrive');

    if(mysqli_errno($conn))
    {

        echo"sum error";
    }
    else
    {
      $email = mysqli_real_escape_string($conn, "a@gmail.com");
      $sql = mysqli_query($conn, 'SELECT * FROM products_bought where email = "'.$email.'"'
        );
         while($row = mysqli_fetch_array($sql)){
          $fullname = $row['fullname'];
        ?>
        <p><?php echo $fullname; ?></p>
        <?php
         }
    }
 ?>

Answer 3

I don't know where the problems came from, but i want to help you a bit :

<?php
   $conn = mysqli_connect('localhost', 'root', '', 'testdrive');
   $sql = mysqli_query($conn,'SELECT * FROM products_bought
    where email = "'.mysqli_real_escape_string($conn, "a@gmail.com").'"');

   if($sql->num_rows > 0){ // Check existence of the data that received
      while($row = mysqli_fetch_array($sql)){
        $fullname = $row['fullname'];
        echo "<p>".$fullname."</p>"; // Why just echoing it in one <?PHP ?>
      }
   } else {
      // If no data sent. then check your db, cause the problems was in your db
   }
?>

Answer 4

the select database please try

   $conn = mysqli_connect('localhost', 'root', '');
    $db = mysqli_select_db('testdrive');

Answer 5

Please check once your database connection done successfully ?

mysqli_connect(DATABASE_HOST, DATABASE_USERNAME, DATABASE_PASSWORD,DATABASE_NAME) or die('Could not connect with server.');

because query you have written is right.