MySQL的选择查询结果为空我怎么能在PHP

Question

返回默认值面对以下错误

Error: Notice: Undefined index: id in /Applications/XAMPP/xamppfiles/htdocs/mks/opencart-1.5.6.1/upload/admin/controller/catalog/vendhqbridge.php on line 120

相关代码：

//check for existing 'VendHQ_id' on DB's product table 

function checkVendHQid($flagChk) 
{ 
$rs = $this->db->query("SELECT vendhq_id as id FROM ".DB_PREFIX."vendhq_product WHERE vendhq_id = '".$flagChk."'"); 

    $rowRsl=-1; 
    if($rs===null) 
    { 
     $rowRsl = -1; 
    } 
    else 
    { 
     if($rs->row["id"] == $flagChk ) 
     { 
      $rowRsl = 1; 
     } 
    } 

    return $rowRsl; 
} 

Answer 1

Vikas Umrao和shadyyx提到，你应该改变查询条件和if条件如下：

变化：

$rs = $this->db->query("SELECT vendhq_id as id FROM ".DB_PREFIX."vendhq_product WHERE vendhq_id = '".$flagChk."'"); 

$rowRsl=-1; 
if($rs===null) 

要：

$rs = $this->db->query("SELECT vendhq_id as id FROM ".DB_PREFIX."vendhq_product WHERE vendhq_id = '".$this->db->escape($flagChk)."'"); 

$rowRsl=-1; 
if(!$rs->num_rows){ 

一个愉快的一天有！

Answer 2

在空格后FROM

$rs = $this->db->query("SELECT vendhq_id as id FROM ".DB_PREFIX."vendhq_product WHERE vendhq_id = '".$flagChk."'");