I'm trying to create a SQL injection example, but MySQL rejects the second query every time unless I change it to mysqli_multi_query.

<form action="<?php echo $_SERVER['PHP_SELF'];?>" method="post" name="dummyDorm">
        <label>Name: </label>
        <input type="text" name="name"><br>
        <input type="submit" value="Submit">
    </form>

    <?php 
        if($_SERVER["REQUEST_METHOD"] == "POST")
        {
            $name = $_POST['name'];
            $conn = mysqli_connect("localhost", "root", "", "testDB");
            if (mysqli_connect_errno()){
                echo "failed to connect" . mysqli_connect_error();
                die();
            }
            else
            {

                $sql = "SELECT * FROM users WHERE name = '{$name}'";
                var_dump($sql);
                if (mysqli_query($conn, $sql))
                {
                    echo "Success";
                } 
                else {
                    echo "Error: " . $sql . "<br>" . mysqli_error($conn);
                }

                mysqli_close($conn);
            }

        }
    ?>

This form doesn't actually do anything, I just want to demonstrate that data can be edited using SQL injection. I want to perform the injection where "DROP TABLE testTable" is entered. My MySQL looks like this:

DROP DATABASE IF EXISTS testDB;
CREATE DATABASE testDB;
USE testDB;

CREATE TABLE users
(
    userID INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(255)
)engine=innodb;

CREATE TABLE testTable
(
    test VARCHAR(10)
)engine=innodb;

INSERT INTO users VALUES(null, "user01");

When entering injection: ';Delete table test table --

The output is as follows: Error: SELECT * FROM users WHERE name = ''; Delete table test table --' There is an error in your SQL syntax; check the manual for your MySQL server version for the correct syntax to use near line 1 "DROP TABLE testTable --"

I continued through the tutorials and they used MySQLi_query and it worked fine, but I had to change it to Mysqli_multi_query to complete the injection.

Thanks