我有这 2 个表，BOOK 和 REVISION，有点像这样:
Book Book_ID | Book_Name | ====================== 1 | Book 1| 2 | Book 2| 3 | Book 3| 4 | Book 4|
Revision Rev_Book_ID | Date_Modified | =========================== 1 | 10/1/2012 | 2 | 10/3/2012 | 2 | 10/5/2012 | 4 | 10/6/2012 |
When a book is being modified the book_id of the book will be save in Revision Table. If that book is being revised again it will add another row of that certain book. In my SQL query the result is this it display the 2 revisions of the book.
Here's my query:
SELECT book.Book_ID, book.Book_Name, Revision.Rev_Book_ID from Book INNER JOIN Revision ON book.Book_ID=Revision.Rev_Book_ID
还有关于修订结果(PHP 问题)，如果这本书被修订两次，我将如何显示 2 个修订或 3 个修订(如果进行了 3 个修订)，我知道这是一个 if 和 else 但没有一个想法如何做到这一点。
My Result: Book ID | Book Name | Revisions | ============================================== 1 | Book 1 | 1 Revision | 2 | Book 2 | 2 Revision | 2 | Book 2 | 2 Revision | 3 | Book 3 | No Revision | 4 | Book 4 | 1 Revision |
Want Result Book ID | Book Name | Revisions | ============================================== 1 | Book 1 | 1 Revision | 2 | Book 2 | 2 Revision | 3 | Book 3 | No Revision | 4 | Book 4 | 1 Revision |
最佳答案
您可以按 book_id 分组并仅选择这些 == 到 MAX(Rev_Book_ID) 的 rev_book_id 通常你想为每本书收集数据。 这是 mysql 规范:http://dev.mysql.com/doc/refman/5.5/en/group-by-functions.html 它应该给你很多想法
关于php - SQL 查询 2 行并且只显示一次具有相同的值，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/19185769/