选择所有带有所有帖子的评论php mysql [英] select all comments with all posts php mysql

问题描述

我有一个论坛，用户可以在其中发布问题，发表评论和发布推文.

I have a forum where users can post questions and can comment and tweet.

我想获取每个帖子的所有comments和tweets.

I want to get all the comments and tweets of each post.

我以前所做的是在3组查询中进行的.

What i did previously was do that in 3 sets queries.

$data = mysqli_query($con,"select * from posts");
while($row = mysqli_fetch_assoc($data)){
  $pid  = $row['post_id'];
  $dataCo = mysqli_query("SELECT comments.* FROM comments WHERE post_id = $pid");
  $dataTw = mysqli_query("SELECT tweets.* FROM tweets WHERE post_id = $pid");
  //2 while loop for comments and tweets

}

任何人都可以告诉我如何在一个查询中执行这些操作，因为如果在第一个查询中有很多posts，那么将有很多查询要做.

Can anyone show me how can i do these things in one single query because if a get a lot of posts in 1st query then there will be lots of queries to do.

OR

也许有更快的方法吗?

推荐答案

也许您可以使用Mysql IN子句

Maybe you can use Mysql IN clause

http://www.tutorialspoint.com/mysql/mysql-in- Clause.htm

在您的示例中，您总是有2 * n + 1个对DB的查询.在此查询中，返回的行数为n

In your example you have always 2*n + 1 queries to DB. Where n in number of returned rows in this query

$data = mysqli_query($con,"select * from posts");

如果使用mysql IN子句，则只有3个查询.

If you use mysql IN Clause you will have only 3 queries.

您的查询应类似于

$dataCo = mysqli_query("SELECT comments.* FROM comments WHERE post_id IN (1,2,3,4)");
$dataTw = mysqli_query("SELECT tweets.* FROM tweets WHERE post_id IN (1,2,3,4)");

数字"1,2,3,4"是您第一个问题中返回的post_id.

Numbers "1,2,3,4" are post_id returned in your first question.

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