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好的,我遇到了這種情況。 3個表格,標籤,書本和交叉表*。你如何處理這一點?使用JOIN的標籤
tags
-id int
-name varchar
books
-id int
-name varchar
taggings
-tagId_fk int
-bookId_fk int
的樣本數據
tags id name 1 good 2 really good 3 bad 4 long 5 exciting books id name 1 Pumpkin Man 2 O-castic Bastard taggings bookId_fk tagId_fk 1 1 1 4 2 4 2 5
所以這裏南瓜人已被標記爲good
和long
而O型castic庶子已被標記爲long
和exciting
。
我想寫檢索單個查詢:不正是我想要
SELECT DISTINCT taggings.bookId_fk, tags.name FROM tags INNER JOIN taggings ON taggings.tagId_fk=tags.tagId ORDER BY taggings.bookId_fk;
這個問題我真的是
books.id books.name taggings.tagId_fk as tags.name (know what I mean?) 1 Pumpkin Man good 1 Pumpkin Man long 2 O-castic Bastard long 2 O-castic Bastard exciting
,它甚至有可能顯示上述結果MySQL無:
- 將其分解爲多個查詢,
- 根本就使用子查詢?
* PS我知道some people don't use an intersection table