Php 如何从其他表中选择实体？

我有一个评论系统，我将新闻ID存储在评论表中，以引用并从新闻表中获取值，我的两个表如下所示

                $query = "SELECT comments.id,
                 comments.timestamp,
                 comments.name,
                 comments.email,
                 comments.phone,
                 comments.location,
                 comments.comment,
                 news.title FROM 
                 comments, news ORDER BY id DESC LIMIT $from, " . COMM_POST_NUMBER;

新表

CREATE TABLE  `news` (
`id` int(20)  NOT NULL auto_increment,
`timestamp` int(20) NOT NULL,
`title` varchar(255) NOT NULL,
`content` text NULL,
`pic_title` varchar(255) NOT NULL,
`pic_brief` varchar(255) NOT NULL,
`pic_detail` varchar(255) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

评论表

CREATE TABLE `comments` (
`id` int(20) NOT NULL auto_increment,
`timestamp` int(20) NOT NULL,
`title` varchar(255) NOT NULL,
`name` varchar(50) NOT NULL,
`email` varchar(50) NOT NULL,
`phone` int(11) NULL,
`location` varchar(50) NOT NULL,
`comment` text NOT NULL,
`approve` tinyint(1) NOT NULL,
`news_id` int(20) NOT NULL,
PRIMARY KEY(`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

在comments表中的news\u id中，我存储了新闻的id，我想从comments表中进行select查询，它应该从news中选择news.title，引用comments表中的news\u id

我做了这样的事

                $query = "SELECT comments.id,
                 comments.timestamp,
                 comments.name,
                 comments.email,
                 comments.phone,
                 comments.location,
                 comments.comment,
                 news.title FROM 
                 comments, news ORDER BY id DESC LIMIT $from, " . COMM_POST_NUMBER;

---

如何使其仅从新闻中获取标题。标题引用评论表中新闻的ID\u ID？

您需要在订单之前添加where子句，方法是：

... FROM comments, news WHERE comments.news_id = news.id ORDER BY ...

使用连接

SELECT comments.id,
             comments.timestamp,
             comments.name,
             comments.email,
             comments.phone,
             comments.location,
             comments.comment,
             news.title 
FROM 
             comments
join news on news.id=comments.news_id
ORDER BY id DESC 
LIMIT .................

两个表都需要：

$query = "SELECT comments.id,
         comments.timestamp,
         comments.name,
         comments.email,
         comments.phone,
         comments.location,
         comments.comment,
         news.title
         FROM comments INNER JOIN news ON comments.news_id = news.id
         ORDER BY id DESC LIMIT $from, " . COMM_POST_NUMBER;

另一个符号是：

FROM comments, news WHERE comments.news_id = news.id

注意：确保对输入进行清理，不要依赖

$from

将其作为整数，强制其为整数：

$from = intval($from);

---

+1为了保持代码整洁以使我理解，如果可以的话，我会给你另一个+1作为intval提示。我实现了它。我唯一的困惑是内部连接和连接。@Ibrahim，检查这里：引用@palehorse:它们的功能相同。内部联接可以更清晰一些，尤其是当查询中包含其他联接类型（如左或右）时。