How to use Count SQL Server Query - sql

Question

i write this post to ask for help on a query on the following schema:
Imagine having two formats, for example, PDF and EBOOK. My goal is to get the following result:
PushiblerName | Number_PDF | Numerber_BOOK |
--------------------------------------------------
ExampleName1 | 2 | 0
ExampleName2 | 3 | 1
Would anyone help me write this query?
Thanks in advance.

Answer 1

select name,(select count(*) from t_book where IdPublisher = t_publisher.Id) as Numerber_BOOK,
(select count(*) from t_book where IdPublisher = t_publisher.Id and IdFormat = 3) as Number_PDF from t_publisher
replace 3 with the Id of Pdf format

Answer 2

Try this:
select P.Name as PublisherName,
SUM(case when F.Code = 'PDF' then 1 else 0 end) as Number_PDF,
SUM(case when F.Code = 'BOOK' then 1 else 0 end) as Number_BOOK
from T_BOOK as B
join T_BOOK_FORMAT as BF on B.Id = BF.BookId
join T_FORMAT as F on BF.IdFormat = F.Id
join T_PUBLISHER as P on B.IdPublisher = P.Id
group by P.Name
I assumed, that format of a book is held in T_FORMAT table in column Code (part with F.Code).

Answer 3

You can use this code,
SELECT publisher.Name as PublisherName,
(SELECT COUNT(*)
FROM T_BOOK book
JOIN T_BOOK_FORMAT bookformat ON book.Id = bookformat.IdBook
JOIN T_FORMAT format ON bookformat.IdFormat = format.Id
WHERE book.IdPublisher = publisher.Id and format.Code='PDF'
) AS Number_PDF,
(SELECT COUNT(*)
FROM T_BOOK book
JOIN T_BOOK_FORMAT bookformat ON book.Id = bookformat.IdBook
JOIN T_FORMAT format ON bookformat.IdFormat = format.Id
WHERE book.IdPublisher = publisher.Id and format.Code='EBOOK'
) AS Number_BOOK
FROM T_PUBLISHER publisher
GROUP BY publisher.Id

Answer 4

I guess you can try something like this
first setup some sample data:
declare #t_book table (Id int, IdPublisher int)
declare #t_publisher table (Id int, Name varchar(50))
declare #t_book_format table (IdBook int, idFormat int)
declare #t_format table (Id int, Description varchar(50))
insert into #t_book values (1, 1), (2, 1), (3, 2), (4, 2), (5, 2), (6, 2)
insert into #t_publisher values (1, 'examplename1'), (2, 'examplename2')
insert into #t_book_format values (1, 1), (2, 1), (3, 2), (4, 1), (5, 1), (6, 1)
insert into #t_format values (1 ,'pdf'), (2, 'book')
now the query :
select p.Name as PublisherName,
f.Description,
count(f.Id) as numbers
from #t_book b
inner join #t_publisher p on b.idPublisher = p.Id
inner join #t_book_format bf on b.Id = bf.idBook
inner join #t_format f on bf.idFormat = f.Id
group by p.Name, f.Description
But without sample data from all tables this is just guessing
The result is in a different format, but it still works if you add more formats in t_book_format and t_format
PublisherName Description numbers
------------- ----------- -------
examplename1 pdf 2
examplename2 book 1
examplename2 pdf 3
If you want to have the list as in you question, you could do a pivot.
But when there is a new format, this new format will not be in the result, so you have to modify the query everytime a new format is added
select * from ( select p.Name,
f.Description,
count(f.Id) as numbers
from #t_book b
inner join #t_publisher p on b.idPublisher = p.Id
inner join #t_book_format bf on b.Id = bf.idBook
inner join #t_format f on bf.idFormat = f.Id
group by p.Name, f.Description
) t
pivot
( sum(numbers)
for Description in (pdf, book)
) piv
the result now looks like this
Name pdf book
---- --- ----
examplename1 2 null
examplename2 3 1
I guess you could put this in a stored procedure and build the last query in dynamic sql, so it would still keep working when you add new formats

Answer 5

Here you go:
CREATE TABLE Author (
AuthorID INT IDENTITY (1,1) PRIMARY KEY NOT NULL,
AuthorName VARCHAR (25) NOT NULL
);
CREATE TABLE Books (
BookID INT IDENTITY (1,1) PRIMARY KEY NOT NULL,
BookName VARCHAR (25) NOT NULL,
BookAothor INT NOT NULL,
CONSTRAINT PK_AuthorOfBook FOREIGN KEY (BookAothor) REFERENCES Author (AuthorID)
);
CREATE TABLE Formats (
FormatID INT IDENTITY (1,1) PRIMARY KEY NOT NULL,
FormatName VARCHAR (10) NOT NULL
);
CREATE TABLE BookFormat (
BookID INT NOT NULL,
FormatID INT NOT NULL,
CONSTRAINT PK_BookFormats PRIMARY KEY (BookID, FormatID),
CONSTRAINT FK_BookRef FOREIGN KEY (BookID) REFERENCES Books (BookID),
CONSTRAINT FK_FormatRef FOREIGN KEY (FormatID) REFERENCES Formats (FormatID)
);
INSERT INTO Author VALUES
('Author1'), ('Author2'), ('Author3');
INSERT INTO Books VALUES
('Book1', 1), ('Book2', 1),
('Book3', 2), ('Book4', 2),
('Book5', 2), ('Book6', 2);
INSERT INTO Formats VALUES
('PDF'), ('E-Book');
INSERT INTO BookFormat VALUES
(1, 1), (2,1),
(3,1), (4,1), (5,1), (6,2);
SELECT A.AuthorName,
ISNULL(Pdf.PdfBooks, 0) AS PdfBooks,
ISNULL(EBook.EBooks, 0) AS EBooks
FROM
Author A LEFT JOIN
(
SELECT A.AuthorID, COUNT(B.BookID) AS PdfBooks
FROM Author A JOIN Books B ON A.AuthorID = B.BookAothor
INNER JOIN BookFormat BF ON B.BookID = BF.BookID
WHERE BF.FormatID =1
GROUP BY A.AuthorID
) Pdf ON A.AuthorID = Pdf.AuthorID
FULL JOIN
(
SELECT A.AuthorID, COUNT(B.BookID) AS EBooks
FROM Author A JOIN Books B ON A.AuthorID = B.BookAothor
INNER JOIN BookFormat BF ON B.BookID = BF.BookID
WHERE BF.FormatID =2
GROUP BY A.AuthorID
) EBook
ON Pdf.AuthorID = EBook.AuthorID;
Results:
+------------+----------+--------+
| AuthorName | PdfBooks | EBooks |
+------------+----------+--------+
| Author1 | 2 | 0 |
| Author2 | 3 | 1 |
| Author3 | 0 | 0 |
+------------+----------+--------+
Here is a demo