查看表SQL Server

我想创建一个视图，显示图书标题和对特定图书的评论数量

当值不兼容时，有哪些选项

Books表中的相关列：

ISBN13 PK bigint
Title nvarchar(50)
Language nvarchar(30)
Author Id FK int
Category ID FK int

样本数据手册：

INSERT INTO Books VALUES (9783852913735, 'Ulysses', 'English', 100, 'January 06, 2002', 1, null);
INSERT INTO Books VALUES (9780195038637, 'Battle Cry of Freedom', 'English', 490, 'February 25, 1988', 99, null);
INSERT INTO Books VALUES (9789178615155, 'Surhörningen', 'Swedish', 195, '2019', 4, null);
INSERT INTO Books VALUES (9789178614577, 'Jag älskar regnbågsenhörningar', 'Swedish', 190, '2021', 2, null);

评审表中的相关列：

ReviewId PK int
BookId FK bigint  -- FK to ISBN13
CategoryID FK
WriterId FK
Date

样本数据审查：

insert into Reviews values(0020, '9783852913735', '120', 11, '2001-02-21');
insert into Reviews values(0021, '9789177836599', '140', 4, '2001-10-19');
insert into Reviews values(0022, '9789178130979', '110', 1, '2002-02-22');
insert into Reviews values(0023, '9789178130979', '90', 8, '2003-09-06');
insert into Reviews values(0024, '9789178614677', '50', 2, '2005-08-29');
insert into Reviews values(0025, '9789178615155', '10', 5, '2004-08-25');
insert into Reviews values(0026, '971019503872', '10', 9, '2009-06-11');
insert into Reviews values(0027, '9780195038637', '20', 2, '2010-11-10');

样本数据类别：

insert into Categories (CategoryId, Name) values(10, 'Architecture');
insert into Categories values(20, 'Art');
insert into Categories values(30,  'Astrology');
insert into Categories values(40,  'Baking');
insert into Categories values(50,  'Business Management');
insert into Categories values(60,  'Biology');
insert into Categories values(70, 'Comics');
insert into Categories values(80,  'Computational Science');

下面是我的评论部分代码，因为我想显示每本书的评论数量：

 SELECT 
    BookId,
COUNT 
    (BookId) [Reviews]
FROM 
    Reviews 
GROUP BY BookId
HAVING COUNT 
    (BookId)> 1

因此，预期结果将是：

Title  |   Author  |  BookId   |   Category   |   Number of Reviews    

---

假设从您的示例查询中，您只经过了一次审阅，您将得到类似的结果（显然是猜测您需要加入的其他表）。有几种关联方法，但简单计数只需要内联关联子查询：

create view MyView as

select 
    b.Title, 
    a.Name Author,
    b.ISBN13 BookId,
    c.Name Category,
    (select Count(*) from Reviews r where r.BookId=b.ISBN13) Reviews
from Books b 
join Categories c on c.Id=b.CategoryId
join Authors a on a.Id=b.AuthorId

使用您添加的数据子集，此查询工作正常

Title                                   BookId     Reviews
------------------------------ --------------- -----------
Ulysses                          9783852913735           1
Battle Cry of Freedom            9780195038637           1
Surhörningen                     9789178615155           1
Jag älskar regnbågsenhörningar   9789178614577           0

---

请查看此查询。我创建了视图，因为类别没有与books表兼容的值，所以我使用左连接来检索在books和review中都有值的记录。请随时对答案进行评论，如果需要，请告诉我任何其他补充或修改。我很乐意帮助你。感谢您发布Insert脚本和表定义，它们为我提供了快速实现和测试功能

CREATE view My_View AS 
(
    SELECT 
        [B].[ISBN13] AS [BookId]
        ,[B].[Title] 
        ,[B].[AuthorId] AS [Author]
        ,[C].[Name] As [Category]
        , COUNT([R].[ReviewId]) OVER ( PARTITION BY [B].[Title]) AS [Number of reviews]
    FROM    Reviews [R] 
        INNER JOIN   Books [B]  
            ON [R].[BookId] = [B].[ISBN13]
        LEFT JOIN Categories [C] 
            ON [B].[CategoryId] = [C].[CategoryId]
            
)


SELECT * FROM My_View 

---

请显示样本数据+预期结果。您很可能需要

转换

或

转换

，以获得匹配的数据类型。您的加入应该是在Reviews.BookId=Books.isbn13为什么您的一些示例

BigInt

值是整数（

9783852913735

）而有些是字符串（

'9783852913735'

）？为什么有些列不需要数据类型，例如

语言

？感谢您的关注，我一直在团队中工作。将更正此问题谢谢，已创建列，但没有值？@EST203谢谢您的编辑-您的评论的图书Id与图书的图书Id不匹配-您的数据模型中的外键是什么？大概你缺了一列。我建议你提供几本书和评论作为样本数据和预期结果，解释每本书是如何获得其评论数的。非常感谢，我希望现在它更清晰了…我用你的样本数据进行了测试，一切都如我预期的那样工作。被上面的定义和数据（例如

Review）弄糊涂了。BookId

和

CategoryId

是一个

字符串，但是查询是正确的。@EST203仍然没有看到预期的结果吗？
CREATE view My_View AS 
(
    SELECT 
        [B].[ISBN13] AS [BookId]
        ,[B].[Title] 
        ,[B].[AuthorId] AS [Author]
        ,[C].[Name] As [Category]
        , COUNT([R].[ReviewId]) OVER ( PARTITION BY [B].[Title]) AS [Number of reviews]
    FROM    Reviews [R] 
        INNER JOIN   Books [B]  
            ON [R].[BookId] = [B].[ISBN13]
        LEFT JOIN Categories [C] 
            ON [B].[CategoryId] = [C].[CategoryId]
            
)


SELECT * FROM My_View