PDO多个SELECT语句

Question

How can i do multiple select statements in one file? For example i have a list of products - i then want to get the stock level's for each of the products. However, it only ever returns the first product, not any other additional products.

$query = $db->query("SELECT * FROM `products` ORDER BY `productName` ASC"); 

    while ($row = $query->fetch(PDO::FETCH_ASSOC)){
    $productId = stripslashes($row['productId']);
    $productName = stripslashes($row['productName']);


    echo "<b>".$productName."</b><br />";


    $query = $db->query("SELECT * FROM `stock` WHERE `productId` = $productId"); 

    while ($row = $query->fetch(PDO::FETCH_ASSOC)){
        $stockId = stripslashes($row['stockId']);
        $stockFilename = stripslashes($row['stockFilename']);

    }
    echo "Stock level= " . $query-> rowCount();

}

Answer 1

Because your second $query is overwriting the first. Rename the second to $query2 (and change the the $query variables to $query2 beneath it). And change $row to $row2

By the way, you can also change your first query into a join to eliminate the second query alltogether.