masukkan ke dalam database dari bidang teks duplikat jika tidak kosong php sql

Pertama-tama cara Anda mendefinisikan variabel Anda saat ini Author_ID2 tidak pernah didefinisikan:

$AuthorTitle = mysqli_real_escape_string($con, ($_POST['AuthorTitle']));
$AuthorTitle = mysqli_real_escape_string($con, ($_POST['AuthorTitle_ID2']));

Di sini Anda hanya mengganti $AuthorTitle dengan nilai dari $_POST['AuthorTitle_ID2'] , dan jangan mendefinisikan $AuthorTitle_ID2 sama sekali.

Selanjutnya, pernyataan SQL seperti yang Anda miliki hanya akan menghubungkan author kedua dengan study dalam casestudy karena LAST_INSERT_ID() akan mengembalikan ID dari record yang terakhir disisipkan meskipun sebenarnya ada beberapa record yang disisipkan oleh satu pernyataan.

Dan terakhir, ada pernyataan JIKA di MySQL :

$AuthorTitle       = mysqli_real_escape_string($con, ($_POST['AuthorTitle']));
$AuthorTitle_ID2   = mysqli_real_escape_string($con, ($_POST['AuthorTitle_ID2']));
$F_Name            = mysqli_real_escape_string($con, ($_POST['first_name']));
$F_Name_ID2        = mysqli_real_escape_string($con, ($_POST['first_name_ID2']));
$L_Name            = mysqli_real_escape_string($con, ($_POST['last_name']));
$L_Name_ID2        = mysqli_real_escape_string($con, ($_POST['last_name_ID2']));
$Email             = mysqli_real_escape_string($con, ($_POST['email']));
$Email_ID2         = mysqli_real_escape_string($con, ($_POST['email_ID2']));
$Contactauthor     = mysqli_real_escape_string($con, ($_POST['contact']));
$Contactauthor_ID2 = mysqli_real_escape_string($con, ($_POST['contact_ID2']));
$Title             = mysqli_real_escape_string($con, ($_POST['Title']));
$Summary           = mysqli_real_escape_string($con, ($_POST['Summary']));

mysqli_multi_query($con,"
START TRANSACTION;
    INSERT INTO study(Title, Summary)
    VALUES('$Title','$Summary');
    SET @StudyId = LAST_INSERT_ID();

    INSERT INTO author(AuthorTitle, F_Name, L_Name, Email, Contact)
    VALUES('$AuthorTitle','$F_Name','$L_Name','$Email','$Contactauthor');
    SET @AuthorId = LAST_INSERT_ID();

    INSERT INTO casestudy(AuthorId, StudyId, Submitted)
    VALUES(@AuthorId, @StudyId, NOW());

    IF ('$AuthorTitle_ID2' <> '' OR '$F_Name_ID2' <> '' OR '$L_Name_ID2' <> '' OR '$Email_ID2' <> '' OR '$Contactauthor_ID2' <> '') THEN
        INSERT INTO author(AuthorTitle, F_Name, L_Name, Email, Contact)
        VALUES('$AuthorTitle_ID2','$F_Name_ID2','$L_Name_ID2','$Email_ID2','$Contactauthor_ID2');
        SET @AuthorId = LAST_INSERT_ID();

        INSERT INTO casestudy(AuthorId, StudyId, Submitted)
        VALUES(@AuthorId, @StudyId, NOW());
    END IF;
COMMIT;
");