MySQL查询，加入我的问题？

Question

我不确定问题，但看看：

我有3张桌子：

1. 类别：id，icon，name;
2. 子类别：id，name，description，category_id;
3. 主题：id，title，text，author，created，subcategory_id;

现在我正在尝试获取此信息（查询）：

  $String = "SELECT
  categories.id AS catid,
  categories.icon AS caticon,
  categories.name AS catname,
  subcategories.id AS scatid,
  subcategories.name AS scatname,
  subcategories.description AS scatdescription,
  subcategories.category_id AS scatcatid,
  COUNT(topics.id) AS tid,
  topics.title AS ttitle,
  topics.author AS tauthor,
  topics.created AS tcreated
       FROM
  categories
LEFT JOIN
  subcategories
ON
  subcategories.category_id = 1
LEFT JOIN
  topics
ON
  subcategories.id = topics.subcategory_id
GROUP BY
 categories.id";

结果：

5分类显示5 - 好的，   4个子类别在第一类中仅显示1个。

也许查询太长了？谢谢你的回答。

Answer 1

此

LEFT JOIN
  subcategories
ON
  subcategories.category_id = 1

应该是这个

LEFT JOIN
  subcategories
ON
  subcategories.category_id = categories.id