Unable to insert into MySQL database with php - php

Question

In this Insert function where I have to insert a book into the database. The author is already existed in the database and I am trying insert a book that is written by the same author. What I am trying to achieve is to prevent user from entering the already existing author that would make duplicate data. When I get to the record the changelog with BookID but I get the a MySQL error where it says
"PDOException: SQLSTATE[HY000]: General error: 1366 Incorrect integer value: 'SELECT BookID from book WHERE BookID = 102' for column 'BookID' at row 1 in C:\wamp64\www\bookprojectdb\Model\bookInsertFunction.php on line 97".
function addBook2($existauthor, $bt, $ot, $yop, $genre, $sold, $lan, $cip, $bp, $ps, $userID){
global $conn;
try {
$conn->beginTransaction();
//Author Data already exist
//Book Data
$stmt = $conn->prepare("INSERT INTO book(BookTitle, OriginalTitle, YearofPublication, Genre,
MillionsSold, LanguageWritten, CoverImagePath, AuthorID)
VALUES(:bt, :ot, :yop, :genre, :sold, :lan, :cip, :authorid);");
$stmt->bindValue(':bt', $bt);
$stmt->bindValue(':ot', $ot);
$stmt->bindValue(':yop', $yop);
$stmt->bindValue(':genre', $genre);
$stmt->bindValue(':sold', $sold);
$stmt->bindValue(':lan', $lan);
$stmt->bindValue(':cip', $cip);
$stmt->bindValue(':authorid',$existauthor);
$stmt->execute();
//BookPlot Data
$lastbookID = $conn->lastInsertID();
$stmt = $conn->prepare("INSERT INTO bookplot(Plot, PlotSource, BookID)
VALUES(:bp, :ps, :bookid);");
$stmt->bindValue(':bp', $bp);
$stmt->bindValue(':ps', $ps);
$stmt->bindValue(':bookid', $lastbookID);
$stmt->execute();
//Changelog Date Create Insert. This inserts date created, bookid and userid.
$datecreated = (date('y-m-d h:m:s'));
$bookID = "SELECT BookID from book WHERE BookID = $lastbookID";
$stmt = $conn->prepare("INSERT INTO changelog(DateCreated, BookID, UserID)
VALUES(:datecreated, :bookid, :userid);");
$stmt->bindValue(':datecreated', $datecreated);
$stmt->bindValue(':bookid', $bookID);
$stmt->bindValue(':userid', $userID);
$stmt->execute();
//commit
$conn->commit();
}
catch(PDOException $ex) {
$conn->rollBack();
throw $ex;
}
}
$existauthor
$query = $conn->prepare("SELECT Name, Surname, AuthorID FROM author WHERE Name = :name AND Surname = :surname");
$query->bindValue(':name', $name);
$query->bindValue(':surname', $surname);
$query->execute();
$row = $query->fetch();
if($query->rowCount() < 1){ //if author doesn't exists
addBook($name, $surname, $nationality, $yob, $yod,
$bt, $ot, $yop, $genre, $sold, $lan, $cip, $bp, $ps, $userID);
header('location:../View/Pages/adminView.php');
}else {
//if author exists
$existauthor = $row['AuthorID'];
addBook2($existauthor,$bt, $ot, $yop, $genre, $sold, $lan, $cip, $bp, $ps, $userID);
header('location:../View/Pages/adminView.php');
}
I thought that by using "lastinsertID();", it would have recorded ID of recently created book. Please Help !

Answer 1

'SELECT BookID from book WHERE BookID = 102' - that is an incorrect integer value indeed.
You have this value assigned to a variable:
$bookID = "SELECT BookID from book WHERE BookID = $lastbookID";
and then you're trying to bind it in place of an integer:
$stmt->bindValue(':bookid', $bookID);

Answer 2

Here's the help you need:
if(!$stmt->execute()) echo $stmt->error;
You ALWAYS should expect errors, and have a workaround, but first you need to check for errors