Php 在SQL中使用通过左联接连接的表登录

我有一个名为“merchant”的表，在登录之前，系统会检查用户名和密码是否匹配。下面的代码使用SQL SELECT进行检查，如果输入正确，则成功进入会话

SQL是

$rowMerchant=$mcMerchant->SelectObj_ByUsrMerchant（$db，$usrmerchant）

您还可以在我的屏幕截图中看到表及其列

现在我想使用一个不同的表，它有自己的用户名和密码，但也使用原始表“merchant_branch”的一些列，hench左连接如下所示

我使用了SQL SelectObj_ByUsrMerchantBranch，在login.vc.php中更改的行是

$rowMerchant = $mcMerchant->SelectObj_ByUsrMerchantBranch($db, $usrmerchant);
$merchantid = $rowMerchant['branchid'];

我刚把merchantid换成branchid，因为这是“merchant_branch”中唯一的密钥。但我无法登录，似乎缺少什么

login.vc.php

  if (isset($_POST['login']) && $_POST['login'] == 'LOGIN')
  {
    $usrmerchant = $_POST['username'] . ' ';

    if ($usrmerchant != '')
    {
      $rowMerchant = $mcMerchant->SelectObj_ByUsrMerchant($db, $usrmerchant);
    }

    if ($rowMerchant['usrmerchant'] != '')
    {
      $passwd = strtoupper(md5($_POST['password'] . $rowMerchant['saltcode']));
      if ($passwd == $rowMerchant['passwd'])
      {
        $merchantid = $rowMerchant['merchantid'];
        $rowAcctCMS = $mcAcctCMS->SelectObj_BySysrefAcctId($db, 1);

        // Assign Session
        $_SESSION['merchantid'] = $merchantid;
        $_SESSION['usrmerchant'] = $rowMerchant['usrmerchant'];
        $_SESSION['accesslevel'] = 'MERCHANT';

        header('Location: orders.php?s=claimed'); die();
      }

Merchant.mc.php

  if (isset($_POST['login']) && $_POST['login'] == 'LOGIN')
  {
    $usrmerchant = $_POST['username'] . ' ';

    if ($usrmerchant != '')
    {
      $rowMerchant = $mcMerchant->SelectObj_ByUsrMerchant($db, $usrmerchant);
    }

    if ($rowMerchant['usrmerchant'] != '')
    {
      $passwd = strtoupper(md5($_POST['password'] . $rowMerchant['saltcode']));
      if ($passwd == $rowMerchant['passwd'])
      {
        $merchantid = $rowMerchant['merchantid'];
        $rowAcctCMS = $mcAcctCMS->SelectObj_BySysrefAcctId($db, 1);

        // Assign Session
        $_SESSION['merchantid'] = $merchantid;
        $_SESSION['usrmerchant'] = $rowMerchant['usrmerchant'];
        $_SESSION['accesslevel'] = 'MERCHANT';

        header('Location: orders.php?s=claimed'); die();
      }

选择Obj_ByUsrMerchant

选择Obj_ByUsrMerchantBranch

  " SELECT
      mb.branchid, mb.merchantid, mb.usrmerchant, m.businessname, m.description, m.address, m.contact, m.email, m.logosrc, m.facebook, m.instagram, m.linkedin, m.twitter, m.googleplus, m.domainpath, m.recstatus, CAST(m.nearby AS UNSIGNED) AS nearby, mb.passwd, mb.saltcode, m.createddate
    FROM `merchant_branch` mb
    LEFT JOIN `merchant` m ON mb.merchantid = m.merchantid
    WHERE
      usrmerchant = :usrmerchant "