使用 php 显示自己和朋友的帖子

Question

我想显示我自己的帖子（默认），但如果Status = '1'也显示朋友的帖子

我只有这段代码，它显示所有带有相关图像和内容的帖子，因为我不知道如何创建我正在寻找的代码。

数据库结构

帖子：

| commentid |  comment  | imagesid | author |
---------------------------------------------
|     1     |   fool    |   5557   | test   |
|     2     |  fool2    |   5585   | devel  |
---------------------------------------------

多个图像：

| id |  image  | imagesid | author |
------------------------------------
| 1  |  name1  |    5557  | test   |
| 2  |  name2  |    5557  | test   |
| 3  |  name3  |    5585  | devel  |
------------------------------------

连接：

| id |  Friend | FriendReferee | Status | 
-----------------------------------------
| 1  |  test   |     devel     |    1   |
-----------------------------------------

---

当前的抓取结构

获取图片的实际代码：

 $sql = "SELECT * FROM multiple_image";
  $result = $conn->query($sql);

  if ($result->num_rows > 0) {
    // output data of each row
    while($row = $result->fetch_assoc()) {
        $imgs[$row['imagesid]][$row['id']]= "<img width='' src='../images/".$row['name']."' >"; // array of image id's, with arrays of images inside them.
  } 

 }

获取相关文本

$sql = "SELECT * FROM posts";
  $result = $conn->query($sql);

  if ($result->num_rows > 0) {
    // output data of each row
    while($row = $result->fetch_assoc()) {
      $commentsToImages[$row['commentid']] = $row['imagesid'];
      $comments[$row['commentid']] = $row['comment']; 
  }     
 }

在分隔的 div 中显示结果

foreach($commentsToImages as $commentID =>$imagesID) {
    ?>
<div class='main'>
  <div class='comments'>


<?php echo $comments[$commentID];?>
  </div>
  <div class='pics'>
    <?php
          foreach($imgs[$imagesID] as $img) { 
                  echo $img;
          }
    ?>
  </div>
</div>

<?php
}
?>

我尝试使用 JOIN 和 if else 语句来实现，但并没有真正按照我的意愿工作。

Answer 1

users、posts 和 connections 表上应该有一个 user_id。 friend_id 还引用了users 表的user_id。

然后你JOINuser_id 上的表posts 和users。通过 id 查找用户名来检索作者。

SELECT
 `p`.`post_id`,
 `p`.`content`    `Post Content`,
 `u`.`user_name`  `Author`
FROM
  `posts`        `p`
INNER JOIN 
  `users`        `u`  USING(`user_id`)
WHERE 
  `p`.`user_id` = 1
;

现在您可以LEFT JOIN 表格connections 发布您想查看的朋友的帖子。您想过滤所有具有特定user_id 的posts 或加入的connection 表具有特定friend_id，例如1:

SELECT
 `p`.`post_id`,
 `p`.`content`    `Post Content`,
 `u`.`user_name`  `Author`
FROM
  `posts`        `p`
INNER JOIN 
  `users`        `u`  USING(`user_id`)
LEFT JOIN
  `connections`  `c`  ON(`c`.`show_posts`  AND  `p`.`user_id` = `c`.`friend_id`)
WHERE 
  1 in (`p`.`user_id`, `c`.`user_id`)
ORDER BY `p`.`post_id`
;

本例使用的数据库结构为：

CREATE TABLE `users`
(
  user_id    INT  NOT NULL  AUTO_INCREMENT  PRIMARY KEY,
  user_name  VARCHAR(20)
)
;

CREATE TABLE `connections`
(
  `user_id`    INT  NOT NULL,
  `friend_id`  INT  NOT NULL,
  `show_posts` BOOL,
  PRIMARY KEY(`user_id`, `friend_id`)
)
;

CREATE TABLE `posts`
(
  `post_id`   INT  NOT NULL  AUTO_INCREMENT  PRIMARY KEY,
  `user_id`   INT  NOT NULL,
  `content`   TEXT(2000)
)
;

INSERT INTO `users`
  (`user_name`)
VALUES
  ('Tom'  ),
  ('Sarah'),
  ('Ben'  )
;

INSERT INTO `connections`
VALUES
  (1,2, true ), -- Tom/Sarah, Tom wants Sarah's posts
  (2,1, false), -- Sarah/Tom, Sarah does not want Tom's posts
  (1,3, false), -- Tom/Ben,   Tom does not want Ben's posts
  (3,1, true )  -- Ben/Tom,   Ben does not want Tom's posts
;

INSERT INTO `posts`
  (`user_id`, `content`)
VALUES
  (1, 'First post by Tom.'   ),
  (2, 'First post by Sarah.' ),
  (1, 'Second post by Tom.'  ),
  (3, 'First post by Ben.'   ),
  (3, 'Second post by Ben.'  ),
  (2, 'Second post by Sarah.'),
  (3, 'Third post by Ben.'   )
;

Try online