Question

我要选择标有一个或多个搜索词的帖子（及其标签）。

这是我的桌子：

发布

| ID | community | created             | updated             | title | content |
|----|-----------|---------------------|---------------------|-------|---------|
| 99 | 17        | 2019-08-14 14:20:38 | 2019-08-14 14:20:38 | Lorem | Ipsum   |
| 80 | 16        | 2019-07-27 23:11:07 | 2019-07-27 23:11:07 | Lorem | Ipsum   |
| 79 | 16        | 2019-07-27 23:09:47 | 2019-07-27 23:09:47 | Lorem | Ipsum   |

社区

| ID | title          |
|----|----------------|
| 16 | The Scary Door |
| 17 | Other          |

社区标签类别

| Community | Category |
|-----------|----------|
| 16        | 5        |
| 16        | 18       |
| 16        | 19       |
| 16        | 20       |
| 17        | 6        |

标签类别

| category    | ID |
|-------------|----|
| character   | 5  |
| focus       | 18 |
| warning     | 19 |
| time-period | 20 |
| NULL        | 6  |

分类标签

| category | tag |
|----------|-----|
| 5        | 146 |
| 6        | 131 |
| 6        | 147 |
| 19       | 147 |
| 20       | 148 |

标签

| name          | id  |
|---------------|-----|
| spider        | 146 |
| arachnophobia | 147 |
| Victorian era | 148 |
| NULL          | 131 |

帖子标签

| post | tag |
|------|-----|
| 99   | 147 |
| 80   | 146 |
| 80   | 147 |
| 80   | 148 |
| 79   | 131 |

我已经在使用此查询来获取有关所有帖子及其相关标签和类别的信息：

SELECT p.id, c.id as 'commid', c.title AS 'community', p.title, p.content, p.author, p.created, p.updated, ct.category, t.name AS 'tag'
FROM Post p, Community c, CommunityTagCategories cc, TagCategory ct, TagCategorised tc, Tag t, PostTags pt
WHERE p.community=c.id AND c.id=cc.community AND cc.category=ct.id AND ct.id=tc.category AND tc.tag=t.id AND t.id=pt.tag AND pt.post=p.id
ORDER BY p.created DESC;

如果我搜索“ arachnophobia”之类的标签，我希望这样缩小搜索范围：（如果我要搜索“ arachnophobia”和“ spider”，则仅应显示80后的信息）

| ID | commid | community      | title | content | author | created             | updated             | category    | tag           |
|----|--------|----------------|-------|---------|--------|---------------------|---------------------|-------------|---------------|
| 99 | 17     | Other          | Lorem | Lorem   | 7      | 2019-08-14 14:20:38 | 2019-08-14 14:20:38 | NULL        | arachnophobia |
| 80 | 16     | The Scary Door | Lorem | Lorem   | 7      | 2019-07-27 23:11:07 | 2019-07-27 23:11:07 | character   | spider        |
| 80 | 16     | The Scary Door | Lorem | Lorem   | 7      | 2019-07-27 23:11:07 | 2019-07-27 23:11:07 | warning     | arachnophobia |
| 80 | 16     | The Scary Door | Lorem | Lorem   | 7      | 2019-07-27 23:11:07 | 2019-07-27 23:11:07 | time-period | Victorian era |

通过搜索类似的问题，似乎我可能需要使用嵌套的SELECT和INNER JOINS。我尝试这样做：

SELECT p2.id, c.id as 'commid', c.title AS 'community', p2.author, p2.created, p2.updated, p2.title, p2.content, tc.category, t.name AS 'tag' 
FROM 
    (SELECT p.id
    FROM Post p, Tag t, PostTags pt
    WHERE p.id=pt.post AND pt.tag=t.id AND t.name ="arachnophobia"
    ) search
INNER JOIN Post p2
ON (search.id = p2.id)
INNER JOIN Community c
ON p2.community=c.id
INNER JOIN CommunityTagCategories cc
ON c.id=cc.community
INNER JOIN TagCategory tc
ON cc.category=tc.id
INNER JOIN TagCategorised ct
ON tc.id=ct.category
INNER JOIN Tag t
ON ct.tag=t.id
INNER JOIN PostTags pt
ON t.id=pt.tag
INNER JOIN Post p3
ON pt.post=p3.id
ORDER BY p2.created DESC;

它确实只返回帖子99和80的结果，但是它为我提供了其关联社区中存在的每个标签和类别的结果，即使这些帖子与那些标签和类别没有关联也是如此。因此，在这里它为帖子80返回了一个额外的行，带有来自帖子79的标签，它们都在同一个社区中。

| ID | commid | community      | title | content | author | created             | updated             | category    | tag           |
|----|--------|----------------|-------|---------|--------|---------------------|---------------------|-------------|---------------|
| 99 | 17     | Other          | Lorem | Lorem   | 7      | 2019-08-14 14:20:38 | 2019-08-14 14:20:38 | NULL        | arachnophobia |
| 80 | 16     | The Scary Door | Lorem | Lorem   | 7      | 2019-07-27 23:11:07 | 2019-07-27 23:11:07 | character   | spider        |
| 80 | 16     | The Scary Door | Lorem | Lorem   | 7      | 2019-07-27 23:11:07 | 2019-07-27 23:11:07 | warning     | arachnophobia |
| 80 | 16     | The Scary Door | Lorem | Lorem   | 7      | 2019-07-27 23:11:07 | 2019-07-27 23:11:07 | time-period | Victorian era |
| 80 | 16     | The Scary Door | Lorem | Lorem   | 7      | 2019-07-27 23:11:07 | 2019-07-27 23:11:07 | character   | NULL          |

几天前，我问过一个类似的问题，即显示所有帖子数据here，而nbk用户帮助了另一个同样有效的查询，但是对于我来说，要知道如何改变自己有点太复杂了。

Answer 1

为避免重复的行，您可以使用DISTINCT

SELECT DISTINCT p2.id
  , c.id as commid
  , c.title AS community
  , p2.author
  , p2.created
  , p2.updated
  , p2.title
  , p2.content
  , tc.category
  , t.name AS tag 
FROM  (
   SELECT p.id
   FROM Post p
   INNER JOIN PostTags pt ON p.id=pt.post
   INNER JOIN Tag t ON  pt.tag=t.id AND t.name ="arachnophobia"
) search
INNER JOIN Post p2 ON search.id = p2.id
INNER JOIN Community c ON p2.community=c.id
INNER JOIN CommunityTagCategories cc ON c.id=cc.community
INNER JOIN TagCategory tc ON cc.category=tc.id
INNER JOIN TagCategorised ct ON tc.id=ct.category
INNER JOIN Tag t ON ct.tag=t.id
INNER JOIN PostTags pt ON t.id=pt.tag
INNER JOIN Post p3 ON pt.post=p3.id
ORDER BY p2.created DESC;

只是一些建议。

您不应在列名前后使用单引号（如果是文字文本，则在需要时使用反引号）。

不应使用旧的基于隐式联接sintax的表名，以逗号分隔，且条件（在子查询中已包含）。

避免加入条件不成功（）

并查看您的关系..您应该避免加入已通过搜索获得的标记的最后一部分

SELECT DISTINCT p2.id
  , c.id as commid
  , c.title AS community
  , p2.author
  , p2.created
  , p2.updated
  , p2.title
  , p2.content
  , tc.category
  , t.name AS tag 
FROM  (
    SELECT p.id
    FROM Post p
    INNER JOIN Tag t ON p.id=pt.post AND t.name ="arachnophobia"
    INNER JOIN PostTags pt ON pt.tag=t.id 
) search
INNER JOIN Post p2 ON search.id = p2.id
INNER JOIN Community c ON p2.community=c.id
INNER JOIN CommunityTagCategories cc ON c.id=cc.community
INNER JOIN TagCategory tc ON cc.category=tc.id
INNER JOIN TagCategorised ct ON tc.id=ct.category
ORDER BY p2.created DESC;

选择所有带有搜索标签的帖子（及相关标签）

1 个答案: