從CodeIgniter（或任何MVC平臺）中的數據庫中提取數據？

Question

我有這樣的型號：

public function index_loop() { 
     $post_user = $this->db->query("SELECT posts.post_title, posts.post_content, posts.post_date, users.username FROM posts LEFT JOIN users ON posts.user_id = users.user_id ORDER BY posts.post_ID DESC"); 
     //$categories = $this->db->query("SELECT categories.cat_name, categories.cat_id FROM 
     //$comments = $this->db->query("SELECT COUNT(comment_id) FROM comments WHERE 
     return $post_user->result_array(); 
    } 

我需要的是要爲每個帖子和評論類（雖然我想，如果我弄清楚路過不是註釋類別是相同的方式）

中查看文件：

<?php foreach($posts as $zz) { ?> 
     <div class="article"> 
      <h2><?php echo $zz['post_title']; ?></h2> 
      <p>Posted by <a href=""><?php echo $zz['username']; ?></a> | Filed under <a href="#">templates</a>, <a href=>internet</a></p> 
      <p><?php echo $zz['post_content']; ?></p> 
      <p><a href=>Read more</a> | <a href=>Comments (5)</a> | <?php echo $zz['post_date']; ?></p> 
     </div> <?php } ?> 

所以，如果我想在每個博客圈類別我需要博客ID，我怎麼得到它，如果我做的型號所有查詢？ 同樣的評論

是不是很好，我做了一個大型複雜的數據庫查詢（這是很難但我能做到）或者我可以做2或3個單獨的較小的查詢？

Answer 1

Codeigniter允許您將數據庫結果作爲對象（例如模型對象）返回，這使得數據更易於使用。您可以將初始查詢發送到Posts表，將posts.id字段包含在結果集中，並將Post_model類的名稱傳遞給$db->query->result()函數，以告知代碼單元您希望將結果作爲實例返回Post_model類。

然後，您可以通過post_id定義對Post_model類GetCategories由post_id和GetComments方法，然後調用這些方法來填充你的$categories和$comments收藏從您的查詢返回的每一Post_model。

下面是一個例子，我希望它能幫助：

<?php foreach($posts as $zz) { ?> 
     <div class="article"> 
      <h2><?php echo $zz->post_title; ?></h2> 
      <p>Posted by <a href=""><?php echo $zz->username; ?></a> | 

       Filed under 
       <?php foreach($zz->categories as $category) { 
         echo '<a href="#">{$category->name}</a>, '; 
        } 
       ?> 
      </p> 
      <p><?php echo $zz->post_content; ?></p> 
      <p><a href=>Read more</a> | <a href=>Comments (5)</a> | <?php echo $zz->post_date; ?></p> 
     </div> <?php } ?> 

至於：

public class Post_model extends CI_Model 
    { 

     // All the properties in the Posts table, as well as a couple variables to hold the categories and comments for this Post: 
     public $id; 
     public $post_title; 
     public $post_content; 
     public $post_date; 
     public $username;   
     public $categories; 
     public $comments; 

     public function index_loop() 
     { 
       return $this->GetAllPosts(); 
     } 

     // function to get all posts from the database, including comments and categories. 
     // returns an array of Post_model objects 
     public function GetAllPosts() 
     { 
       // define an empty array to hold the results of you query. 
       $all_posts = array(); 

       // define your sql query. NOTE the POSTS.ID field has been added to the field list 
       $sql = "SELECT posts.id, 
           posts.post_title, 
           posts.post_content, 
           posts.post_date, 
           users.username 
         FROM posts LEFT JOIN users ON posts.user_id = users.user_id 
         ORDER BY posts.post_id DESC"; 

       // issue the query 
       $query = $this->db->query($sql); 

       // loop through the query results, passing a string to result() which represents a class to instantiate 
       //for each result object (note: this class must be loaded) 

       foreach($query->result("Post_model") as $post) 
       { 
         $post->categories = $this->GetPostCategories($post->id); 
         $post->comments = $this->GetPostComments($post->id); 
         $all_posts[] = $post; 
       } 

       return $all_posts; 
     } 

     // function to return categories for a given post_id. 
     // returns an array of Category_model objects. 
     public function GetPostCategories($post_id) 
     { 
       $sql = "SELECT category.id, ... WHERE post_id = ?"; 
       $query = $this->db->query($sql, array($post_id)); 
       $categories = array(); 
       foreach($query->result("Category_model") as $category) 
       { 
         $categories[] = $category; 
       } 
       return $categories; 
     } 

     // function to return comments for a given post_id. 
     //returns an array of Comment_model objects 
     public function GetPostComments($post_id) 
     { 
       $sql = "SELECT comment.id, ... WHERE post_id = ?"; 
       $query = $this->db->query($sql, array($post_id)); 
       $comments = array(); 
       foreach($query->result("Comment_model") as $comment) 
       { 
         $comments[] = $comment; 
       } 
       return $comments; 
     }  
} 

然後，在你看來，你可以爲Post_model對象，而不是作爲result_arrays訪問$帖子陣列效率問題，它將取決於很多因素（數據庫與Web服務器位於同一臺計算機上，有多少帖子等等）。單個大型查詢通常會比幾個小型查詢執行得更快，但需要通過分析來真正確定性能增益是否值得尋求。我總是傾向於嘗試編寫可讀/可理解的代碼，而不是以增加複雜性爲代價進行優化。

Answer 2

你可以做1件事。

作出不同的分類表和評論表。

category_id將與post_table中的category_id列相鏈接。

在評論表中，創建將與post_id中的post_id鏈接在一起的列post_id。

然後您可以通過此擴展查詢一次檢索所有信息。

$post_user = $this->db->query("SELECT posts.post_title, posts.post_content, posts.post_date, users.username FROM posts LEFT JOIN users ON posts.user_id = users.user_id LEFT JOIN category ON category.category_id = post.category_id ORDER BY posts.post_ID DESC"); 

在這裏你得到了類別。

對於評論，我不知道你想如何輸出。 Yan說，一種方法是。如果你可以更具體，我可以建議一些更簡單的方法。