此问题已解决(在页面底部编辑(
foreach语句中查询的输出出现问题。出于某种原因，变量的转储会给出NULL NULL等，而不是表Items的正确输出。有人知道是什么原因造成的吗？
<?php
$offers_array = array();
$query = "select trade_offer.*, gebruikers.naam, gebruikers.image_url from trade_offer join gebruikers on gebruikers.id = trade_offer.sender_id where receiver_id = ?";
$stmt = $db->prepare($query);
$stmt-> bind_param('i', $gebruiker->id);
$stmt->execute();
$result = $stmt->get_result();
while ($row = $result->fetch_assoc()){
$offers_array[] = $row;
}
foreach($offers_array as $offer){
$query_fetch = "select * from items where id in (?,?,?,?,?,?,?,?)";
$stmt = $db->prepare($query_fetch);
$stmt-> bind_param('iiiiiiii', $offer['receiver_gets_1'], $offer['receiver_gets_2'], $offer['receiver_gets_3'], $offer['receiver_gets_4'], $offer['sender_gets_1'], $offer['sender_gets_2'], $offer['sender_gets_3'], $offer['sender_gets_4']);
$stmt->execute();
$stmt->bind_result($col1, $col2, $col3, $col4);
while($stmt->fetch()){
$id = $col1;
$naam = $col2;
$prijs = $col3;
$image = $col4;
echo $id;
echo $naam;
echo $prijs;
echo $image;
}
}?>
抛售$offer：
Array
(
[id] => 8
[receiver_id] => 2
[sender_id] => 3
[receiver_gets_1] => 10
[receiver_gets_2] => 15
[receiver_gets_3] => 18
[receiver_gets_4] => 13
[sender_gets_1] => 19
[sender_gets_2] => 14
[sender_gets_3] => 17
[sender_gets_4] => 9
[accepted] =>
[naam] => John
[image_url] => http://www.example.com/img.jpg
)
项目表内容：
id naam prijs image_url
1 item1 2.00 example.com
2 item2 2.00 example.com
3 item3 2.00 example.com
4 item4 2.00 example.com
5 item5 2.00 example.com
6 item6 2.00 example.com
etc.
谢谢！
编辑：我根据Kim Alexander的回答编辑了我的代码，现在出现了以下错误：Fatal error: Call to a member function bind_param() on boolean in ......'tradeoffers.php on line 31
第31行：
$stmt-> bind_param('iiiiiiii', $offer['receiver_gets_1'], $offer['receiver_gets_2'], $offer['receiver_gets_3'], $offer['receiver_gets_4'], $offer['sender_gets_1'], $offer['sender_gets_2'], $offer['sender_gets_3'], $offer['sender_gets_4']);
我想你的意思不是：
$result = $stmt->get_result($col1, $col2, $col3, $col4);
while($stmt->fetch()){
$id = $col1;
$naam = $col2;
但是
$stmt->bind_result($col1, $col2, $col3, $col4);
while($stmt->fetch()){
$id = $col1;
$naam = $col2;