Undefined variable BEFORE SUBMIT is clicked

Question

At first, when I don't use the submit button, there is undefined variable error

Notice: Undefined variable: results in C:\xampp\htdocs\01test\index.php on line 31

Warning: mysqli_fetch_array() expects parameter 1 to be mysqli_result, null given in C:\xampp\htdocs\01test\index.php on line 31

The code works when submit has been used.

This is my code [a link](https://pastebin.com/geBjQDGC/)!

Everything works fine after the submit button has been used. But before use it at first, there is two error.

Hasitha Jayawardana · Accepted Answer · 2019-09-11T06:14:38.663

Notice: Undefined variable: results in C:\xampp\htdocs\01test\index.php on line 31

According to the above error the statement on line 31 is,

while($row = mysqli_fetch_array($results))

So according to the error, the problem is in the following statement.

$results = mysqli_query($dblink, $query) or die (mysqli_error());

The above statement is inside your if-else statement. Since you have declared that variable and assigned inside the if statement you will get that error because it can't be accessed from the outside. So I suggest you declare the variable $results outside the if statement. But hold on you have another error.

Warning: mysqli_fetch_array() expects parameter 1 to be mysqli_result, null given in C:\xampp\htdocs\01test\index.php on line 31

$results = mysqli_query($dblink, $query) or die (mysqli_error());

From the following statement you are parsing the above variable,

while($row = mysqli_fetch_array($results))

So your $results is in the if-else statement. But you have called it from outside the if statement in mysqli_fetch_array(). Your if condition is checking that you submit the post or not. Since you are not submitted and your following code

while($row = mysqli_fetch_array($results))

is outside the if condition $results give you null value. In brief your code while($row = mysqli_fetch_array($results)) is calling $results if you submitted the post or not. So now you can understand what is the issue.

So finally, your code should be like this,

<?php
    $servername = "localhost";
    $username = "root";
    $password = "";
    $database = "abc";

    $dblink = mysqli_connect($servername,$username,$password,$database);

    if(isset($_POST['submit'])) {
        if($_POST['select']=='all_records') {
            $query = "SELECT Kod_Dorm FROM dorm";
        } elseif($_POST['select']=='A302') {
            $query = "SELECT Kod_Dorm FROM dorm WHERE Kod_Dorm = 'A302'";
        } elseif($_POST['select']=='A303') {
            $query = "SELECT Kod_Dorm FROM dorm WHERE Kod_Dorm = 'A303'";
        }

        $results = mysqli_query($dblink, $query) or die (mysqli_error());

        echo "<table>"; // start a table tag in the HTML

        while($row = mysqli_fetch_array($results)) {   //Creates a loop to loop through results
            echo "<tr><td>".$row['Kod_Dorm']."</td></tr>";  //$row['index'] the index here is a field name
        }

        echo "</table>"; //Close the table in HTML

    }
?>

By putting the following code inside the if statement will solve your problem because if you only submit the form then it will fetch values. Hope this helps you!

echo "<table>"; // start a table tag in the HTML

while($row = mysqli_fetch_array($results)) {   //Creates a loop to loop through results
    echo "<tr><td>".$row['Kod_Dorm']."</td></tr>";  //$row['index'] the index here is a field name
}

echo "</table>"; //Close the table in HTML

Undefined variable BEFORE SUBMIT is clicked

1 Answers1