Question

我一直在使用mysqli获取要返回的行数时遇到问题。尽管肯定有一些结果，但我每次都会得到0。

if($stmt = $mysqli->prepare("SELECT id, title, visible, parent_id FROM content WHERE parent_id = ? ORDER BY page_order ASC;")){  
    $stmt->bind_param( s , $data->id);  
    $stmt->execute();
    $num_of_rows = $stmt->num_rows;  
    $stmt->bind_result($child_id, $child_title, $child_visible, $child_parent);  

    while($stmt->fetch()){
        //code
    }

    echo($num_of_rows);

    $stmt->close();
}

为什么它没有显示正确的数字？

Answer 1

您需要拨打mysqli_stmt:：store_result（）在num_rows查找之前：

if($stmt = $mysqli->prepare("SELECT id, title, visible, parent_id FROM content WHERE parent_id = ? ORDER BY page_order ASC;")){  
    $stmt->bind_param( s , $data->id);  
    $stmt->execute();
    $stmt->store_result(); <-- This needs to be called here!
    $num_of_rows = $stmt->num_rows;  
    $stmt->bind_result($child_id, $child_title, $child_visible, $child_parent);  

    while($stmt->fetch()){
        //code
    }

    echo($num_of_rows);

    $stmt->close();
}

请参阅mysqli_stmt:：num_rows，它就在页面顶部附近（在主描述块中）。

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