在连接查询中使用多个和条件

Question

如果帖子中的值不等于空白，我想加入查询，并且当两个帖子值中的值都可以完美运行时。问题是当该值仅在一个帖子中时，AND 位于任何其他第二个值之前。希望得到解决方案。我正在使用核心 PHP

if(!empty($_POST['agent_wise'])){       
    $agent_wise = $_POST['agent_wise'];
    $queryCondition .= "allusers.sno ='$agent_wise'";
} 

if(!empty($_POST['status_wise'])){      
    $status_wise = $_POST['status_wise'];
    $queryCondition .= " AND st_application.admin_status_crs ='$status_wise'";
}   
if(!empty($_POST['course_wise'])){      
    $course_wise = $_POST['course_wise'];
    $queryCondition .= " AND st_application.prg_name1 ='$course_wise'";
}


$result2 = "SELECT * FROM st_application INNER JOIN allusers on st_application.user_id = allusers.sno where " . $queryCondition . " ";

Answer 1

试试这个代码。

if(!empty($_POST['agent_wise'])){      
    $agent_wise = $_POST['agent_wise'];
    $queryCondition .= "allusers.sno ='$agent_wise'";
 } 

if(!empty($_POST['status_wise'])){      
    $status_wise = $_POST['status_wise'];
    $queryCondition .= " AND st_application.admin_status_crs ='$status_wise'";
}   

if(!empty($_POST['course_wise'])){      
    $course_wise = $_POST['course_wise'];
    $queryCondition .= " AND st_application.prg_name1 ='$course_wise'";
}


$queryCondition = trim($queryCondition, 'AND'); 


$result2 = "SELECT * FROM st_application INNER JOIN allusers on st_application.user_id = allusers.sno where " . $queryCondition . " ";

希望对你有帮助

Answer 2

这里有解决方案...

$flag = 0;
if(!empty($_POST['agent_wise'])){ 
        $flag = 1;    
        $agent_wise = $_POST['agent_wise'];
        $queryCondition .= "allusers.sno ='$agent_wise'";
     } 

if(!empty($_POST['status_wise'])){      
        $status_wise = $_POST['status_wise'];
        if($flag == 1){
        $queryCondition .= " AND st_application.admin_status_crs ='$status_wise'";
        }
      else {
        $queryCondition .= " st_application.admin_status_crs ='$status_wise'";
         $flag = 1;
  }
    }   
    if(!empty($_POST['course_wise'])){      
        $course_wise = $_POST['course_wise'];
       if ($flag == 1){
        $queryCondition .= " AND st_application.prg_name1 ='$course_wise'";
      }
       else {
           $queryCondition .= " st_application.prg_name1 ='$course_wise'";
    }
    }


$result2 = "SELECT * FROM st_application INNER JOIN allusers on st_application.user_id = allusers.sno where " . $queryCondition . " ";

Answer 3

懒惰的技巧是在第一个条件中也包含AND，并将WHERE 更改为WHERE 1，但我怀疑有更智能且易于搜索的方法来解决这个问题。哦，还有关于sql注入和prepared statements的重要性

Answer 4

在连接“AND”之前检查空字符串。

$queryCondition .=  (empty($queryCondition) ? "" : " AND ") . 
    "st_application.admin_status_crs ='$status_wise'"

Answer 5

您的问题有两种解决方案。一种 SQL 方案和一种 PHP 方案：

第一个解决方案

if(!empty($_POST['agent_wise'])){       
    $agent_wise = $_POST['agent_wise'];
    $queryCondition .= " AND allusers.sno ='$agent_wise'";
} 

if(!empty($_POST['status_wise'])){      
    $status_wise = $_POST['status_wise'];
    $queryCondition .= " AND st_application.admin_status_crs ='$status_wise'";
}   
if(!empty($_POST['course_wise'])){      
    $course_wise = $_POST['course_wise'];
    $queryCondition .= " AND st_application.prg_name1 ='$course_wise'";
}


$result2 = "SELECT * FROM st_application INNER JOIN allusers on st_application.user_id = allusers.sno where TRUE" . $queryCondition . " ";

这是有效的，因为在 WHERE TRUE AND 'something else' 中，TRUE 条件是多余的。唯一的缺点是，如果没有任何 POST 存在，您将获得所有记录，因为 WHERE TRUE 总是带回记录。但是您可以轻松地进行检查以查看所有 POST 是否存在，如果不存在则退出：

if (empty($_POST['agent_wise']) && empty($_POST['status_wise']) && empty($_POST['course_wise']) ) exit;

第二个解决方案

$queryConditionsArray = [];

if(!empty($_POST['agent_wise'])){       
    $agent_wise = $_POST['agent_wise'];
    $queryConditionsArray[] = "allusers.sno ='$agent_wise'";
} 

if(!empty($_POST['status_wise'])){      
    $status_wise = $_POST['status_wise'];
    $queryConditionsArray[] = "st_application.admin_status_crs ='$status_wise'";
}   
if(!empty($_POST['course_wise'])){      
    $course_wise = $_POST['course_wise'];
    $queryConditionsArray[] = "st_application.prg_name1 ='$course_wise'";
}

$queryCondition = implode(' AND ', $queryConditionsArray);

$result2 = "SELECT * FROM st_application INNER JOIN allusers on st_application.user_id = allusers.sno where " . $queryCondition . " ";

这是可行的，因为 implode 只会在条件之间插入单词“AND” - 而不是在每个条件的开头。同样，您必须检查是否没有 POST，否则您的 SQL 将失败。

我个人更喜欢第二种方式，但要视情况而定。