MySQL where語句中的where語句

Question

在現有的MySQL循環中，WHERE語句似乎有問題，這使我認為這是不可能的。 如果可行，我將如何執行？

這個例子使用了它現有的連接，我也嘗試了自己的連接沒有成功。

我有2個表， 預訂和工作 .. 預定是數據庫的主要描述部分和工作可能涉及從預訂的預訂幾行

<?php
    $conn = mysqli_connect($servername,$username,$password,$dbname);

    if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
    }

    $sql = "SELECT * FROM rwxoq_Bookings WHERE user_id = $user_id";
    $result = mysqli_query($conn, $sql);
    while($rowb = mysqli_fetch_assoc($result)) { 
?>
    <tr>
      <td valign="top">
        <?php echo $rowb{'Booking_ID'};?>
      </td>
      <td>
       <?php echo date("D, d-m-Y g:ia", strtotime($rowb{'created'}));?>
      </td>
      <td>
        <?php
         $sqlj = "SELECT * FROM rwxoq_jobs WHERE Booking_ID = $rowb{'Booking_ID'}";
         $resultj = mysqli_query($conn, $sqlj);
         while($rowj = mysqli_fetch_assoc($resultj)) {
             $count++;
         }
        echo $count;
?>
      </td>
      <td id="<?php echo $row{'id'};?>">PENDING</td>
    </tr>
<?php } ?>

Answer 1

我知道您會怎么做，但這不是一個好的解決方案。
我建議您在表之間使用聯接：

 $conn = mysqli_connect($servername,$username,$password,$dbname); if ($conn->connect_error) { die("Connection failed: " . $conn->connect_error); } $sql = "SELECT b.*, COUNT(*) AS cnt FROM rwxoq_Bookings b LEFT JOIN rwxoq_jobs j ON j.Booking_ID = b.Booking_ID WHERE user_id = $user_id GROUP BY b.Booking_ID"; $result = mysqli_query($conn, $sql); $table = ""; while($rowb = mysqli_fetch_assoc($result)) { $table .= " <tr> <td valign='top'> {$rowb['Booking_ID']} </td> <td> ". date('D, dmY g:ia', strtotime($rowb['created'])) ." </td> <td> {$rowb['cnt']} </td> <td id='{$row['id']}'>PENDING</td> </tr>"; } echo $table;