PDO - 在“while”循环中获取 Assoc

Question

我正在尝试在 while 循环中回显一些 html。我正在使用 PDO 和 PDO_ASSOC 获取我的东西。

这就是我所拥有的：

$stmt = $this->conn->prepare('SELECT * FROM books');
$stmt->execute();
while($row = $stmt->fetch(PDO::FETCH_ASSOC))
{
    $book_id = $row['id'];
    $book_title = $row['title'];
    $book_image = $row['image'];
    $book_amz = $row['amazon'];
    $book_desc = $row['description'];
    $book_rating = $row['rating'];
    $book_date = $row['date'];
    $book_author = $row['author'];
    $book_categorie = $row['categorie'];
    $text = "ID: ' . $book_id . '";
 }
 return $text;

但它只给了我表格的一排。我什至尝试过fetchAll，但它什么也没给我。

Answer 1

因此假设唯一见过的元素是最后一个元素，因为您返回的内容在每个循环中都会被覆盖。有几个选项可以解决这个问题。最简单的是：

$stmt = $this->conn->prepare('SELECT * FROM books');
$stmt->execute();

$text = "";
while($row = $stmt->fetch(PDO::FETCH_ASSOC))
{
    $book_id = $row['id'];
    $book_title = $row['title'];
    $book_image = $row['image'];
    $book_amz = $row['amazon'];
    $book_desc = $row['description'];
    $book_rating = $row['rating'];
    $book_date = $row['date'];
    $book_author = $row['author'];
    $book_categorie = $row['categorie'];

    //String concatenation of text will 
    //give you one big string at the end to return.   
    $text .= "ID: '{$book_id}'";
}
return $text;

但是，这不适用于您真正的引导 html。您需要确保这些列相加正确。

你需要一些更直观的东西

使用实际代码看起来像

$stmt = $this->conn->prepare('SELECT * FROM books');
$stmt->execute();

$bookEcho = array();
while($row = $stmt->fetch(PDO::FETCH_ASSOC)){
    $bookEcho[] = '<div class="col-md-3">
                   <div class="thumbnail">
                   <span>' . $book_title . '</span>
                   <img src="' . $book_image . '">
                   <div class="book-options">
                   <span>Bewertung</span><br/>
                   ' . $stars . '
                   <a href="books.php?id=' . $book_id . '" class="btn btn-read btn-block">Jetzt lesen</a>
                   </div>
                   </div>
                   </div>';
}
return $bookEcho;

现在在你的函数中你可以做类似的事情（这不是我写过的最优雅的东西，但应该可以完成工作）：

$cols = 4;
$colCount = 1;
foreach ($bookEcho as $book){
    if($colCount == 0){//create a row}
    echo $book;
    $coolCount++;
    if($colCount == 0){end a row}
    if($colCount == 4){ $colCount = 0;}
}

Answer 2

问题是您在 while 循环中覆盖了您的值。对于数据库中的每个条目，循环都会执行一次，但只会返回最后一个。相反，您想使用数组：

$stmt = $this->conn->prepare('SELECT * FROM books');
$stmt->execute();
$books = [];
while($row = $stmt->fetch(PDO::FETCH_ASSOC))
{
    $book['id'] = $row['id'];
    $book['title'] = $row['title'];
    $book['image'] = $row['image'];
    $book['amz'] = $row['amazon'];
    $book['desc'] = $row['description'];
    $book['rating'] = $row['rating'];
    $book['date'] = $row['date'];
    $book['author'] = $row['author'];
    $book['categorie'] = $row['categorie'];
    $book['text'] = "ID: ' . {$book['id']} . '"; // << Not sure if this is what you actually want. If not, adjust accordingly.

    // Append the above values to the $books array
    $books[] = $book;
}
return $books;

Answer 3

使用foreach：

$books = $stmt->fetchAll(PDO::FETCH_ASSOC);
foreach($books as $book){
    $book_id = $book['id'];
    $book_title = $book['title'];
    // ...
}