數據是從數據庫中檢索到的，但不會插入？

Question

因此，當我想檢索數據並檢查它時，即電子郵件是否已經存在，回聲已經注冊。 該部分工作正常，但是無法插入相同的數據。 我的附帶條件是否訂購不正確？ （故意遺漏了dbhostname id pw變量的值）

$dbname = "hw2";

$link = mysqli_connect($dbhostname, $dbuserid, $dbpassword, $dbname);

$firstname = $_POST["signup-firstname"];
$lastname = $_POST["signup-lastname"];
$email = $_POST["signup-email"];
$password = $_POST["signup-password"];
$repassword = $_POST["signup-repassword"];

if ($password != $repassword){
    echo "<br><h3>Passwords did not match. <br>Please try again.</h3>";
}

else {

$ret_email = "SELECT * FROM hw2 WHERE email = '$email'";
$result = mysqli_query($link, $ret_email);
$num_rows = mysqli_num_rows($result);

    if ($num_rows > 0){
    echo "This email is already registered.";
    }   

    else{
    $insert_query = "INSERT INTO hw2 (firstname, lastname, email, password, repassword) VALUES ('$firstname', '$lastname', '$email', '$password', '$repassword')";
    echo "$insert_query";
    }       
}
?>

Answer 1

您不僅應執行查詢，還應執行查詢

mysqli_query($con,"INSERT INTO Persons (FirstName,LastName,Age) 

if ($num_rows > 0){
echo "This email is already registered.";
}   

else{
$insert_query = "INSERT INTO hw2 (firstname, lastname, email, password, repassword) VALUES ('$firstname', '$lastname', '$email', '$password', '$repassword')";

echo "$insert_query";
mysqli_query($link,$insert_query)
}