Php 从数据库中选择多个类别

我正在开发一个博客系统，其中博客被分类，我们可以选择我们想要的类别。为此，我必须将表

blogs

和

类别

分开。我知道如何从所有类别和单个类别中获取博客，但我不知道如何从多个类别（但不是所有类别）获取博客

我的代码如下所示：

 <?php
   $query = ("SELECT blogs_id, title, body, posted_by, category FROM blogs INNER JOIN categories ON categories.category_id=blogs.category_id where category='cat1' ORDER BY blogs_id desc LIMIT 10");
   $result = mysql_query($query) or die("error:".mysql_error());
    while ($row = mysql_fetch_assoc($result)) {
        $title = $row['title'];
        $body = $row['body']; 
        $posted_by = $row['posted_by'];
      ?>

使用以下子句：

或者，您可以使用：

尝试用
或
代替
和
（在where条件下）。试试这个：

$query = ("SELECT blogs_id, title, body, posted_by, category FROM blogs INNER JOIN categories ON categories.category_id=blogs.category_id where category='cat1' OR category='cat2' OR category='cat3' ORDER BY blogs_id desc LIMIT 10");

试试这个

$query = ("SELECT blogs_id, title, body, posted_by, category FROM blogs INNER JOIN categories ON categories.category_id=blogs.category_id where category IN ('cat1', 'cat2', 'cat3') ORDER BY blogs_id desc LIMIT 10");

WHERE category = 'cat1'
   OR category = 'cat2'
   OR category = 'cat3'

$query = ("SELECT blogs_id, title, body, posted_by, category FROM blogs INNER JOIN categories ON categories.category_id=blogs.category_id where category='cat1' OR category='cat2' OR category='cat3' ORDER BY blogs_id desc LIMIT 10");

$query = ("SELECT blogs_id, title, body, posted_by, category FROM blogs INNER JOIN categories ON categories.category_id=blogs.category_id where category IN ('cat1', 'cat2', 'cat3') ORDER BY blogs_id desc LIMIT 10");