Sql 多次提供相同主键值时获取唯一搜索数据

让我展示一下表的结构

书桌

DECLARE @Book TABLE (BookID INT, BookName VARCHAR(30))

INSERT INTO @Book
    (BookID, BookName)
SELECT '1', 'Art of Programming Contest' UNION ALL  
SELECT '2', 'Programming in C' UNION ALL
SELECT '3', 'Programming in C++'

--SELECT * FROM @Book

图书作者表

DECLARE @BookAuthors TABLE (BookID INT, AuthorID INT)

INSERT INTO @BookAuthors
    (BookID, AuthorID)
SELECT '1', '1' UNION ALL
SELECT '1', '2' UNION ALL
SELECT '2', '1' UNION ALL
SELECT '2', '3' UNION ALL
SELECT '3', '2' UNION ALL
SELECT '3', '4'

--SELECT * FROM @BookAuthors

图书分类表

DECLARE @BookCategories TABLE (BookID INT, CategoryID INT)

INSERT INTO @BookCategories
    (BookID, CategoryID)
SELECT '1', '1' UNION ALL
SELECT '1', '2' UNION ALL
SELECT '2', '1' UNION ALL
SELECT '2', '3' UNION ALL
SELECT '3', '2' UNION ALL
SELECT '3', '4'

--SELECT * FROM @BookCategories

通过使用这些表，我想按

BookID

、

AuthorID

和

CategoryID

搜索书籍；对于

AuthorID

和

CategoryID

搜索，我需要分别加入

BookAuthors

和

BookCategories

表。但是当我尝试通过

AuthorId

搜索时，结果多次给出相同的

BookId

查询

SELECT BK.BookID, BA.AuthorID, BC.CategoryID 
FROM @Book BK
LEFT JOIN @BookAuthors BA ON BA.BookID = BK.BookID
LEFT JOIN @BookCategories BC ON BC.BookID = BK.BookID
WHERE BA.AuthorID = 1

结果

BookID  ----- AuthorID ----- CategoryID 
   1             1               1
   1             1               2
   2             1               1
   2             1               3

我认为，到目前为止，它是好的；现在，我想生成如下结果：

BookID  ----- AuthorIDs ----- CategoryIDs
   1             1,2             1,2
   2             1,3             1,3

---

有什么想法吗？

我不知道你为什么希望结果像这样输出，我认为这不是一个好主意

但是你可以用这个

rextester演示：

返回：

+--------+-----------+-------------+
| BookId | AuthorIds | CategoryIds |
+--------+-----------+-------------+
|      1 | 1,2       | 1,2         |
|      2 | 1,3       | 1,3         |
+--------+-----------+-------------+

---

可能与我相同的副本，+1:）

+--------+-----------+-------------+
| BookId | AuthorIds | CategoryIds |
+--------+-----------+-------------+
|      1 | 1,2       | 1,2         |
|      2 | 1,3       | 1,3         |
+--------+-----------+-------------+