定義查詢中的列名和限制數據

Question

我使用PDO bindParam()可以在查詢中定義列名。

這是我到目前爲止

編輯嘗試：

$item = "Fruits"; 
$num = "5"; 
$tot = (int)$num; 

$sql = "SELECT categories.item, price.:itm 
      FROM categories 
       LEFT JOIN price 
        ON categories.iID = price.iID 
         WHERE price.:itm = :availability 
          ORDER BY categories.item 
           ASC LIMIT :lmt"; 
$stmt = $connect->prepare($sql); 
$stmt->bindParam(':itm', $item); 
$stmt->bindParam(':lmt', $tot); 
$stmt->execute(array(':availability'=>"1")); 
$mulu = $statementa->fetchColumn(); 

我怎麼能算和限制5分的結果？

Answer 1

您不能綁定列，只值：

$sql = "SELECT categories.item, price.$item 
      FROM categories 
       LEFT JOIN price 
        ON categories.iID = price.iID 
         WHERE price.$item = :availability 
          ORDER BY categories.item 
           ASC LIMIT :lmt"; 
$stmt = $connect->prepare($sql); 
#$stmt->bindParam(':itm', $item); 
$stmt->bindParam(':lmt', $tot); 
$stmt->execute(array(':availability'=>"1")); 
$mulu = $statementa->fetchColumn();