Question

I am wondering if it is possible and more efficient to do something that I am presently doing in code, to do in T-SQL instead.

I have a database with courses. Each course can have different offerings which are variations of the course at different locations and at different awards.

Here’s my (simplified) database structure and some sample data:

CREATE TABLE tblCourse (CourseId int, CourseName varchar(50))
CREATE TABLE tblOffering (OfferingId int, CourseId int, LocationId int, AwardId int)
CREATE TABLE tblLocation (LocationId int, LocationName varchar(50))
CREATE TABLE tblAward (AwardId int, AwardName varchar(50))

INSERT INTO tblCourse VALUES (1, 'Course A')
INSERT INTO tblCourse VALUES (2, 'Course B')

INSERT INTO tblOffering VALUES (1, 1, 1, 1)
INSERT INTO tblOffering VALUES (2, 1, 2, 1)
INSERT INTO tblOffering VALUES (3, 1, 3, 1)
INSERT INTO tblOffering VALUES (4, 1, 1, 2)
INSERT INTO tblOffering VALUES (5, 2, 3, 1)

INSERT INTO tblLocation VALUES (1, 'Location A')
INSERT INTO tblLocation VALUES (2, 'Location B')
INSERT INTO tblLocation VALUES (3, 'Location C')

INSERT INTO tblAward VALUES (1, 'Award A')
INSERT INTO tblAward VALUES (2, 'Award B')

What I want to retrieve from SQL is a single row for each course/award combination. Each row would have columns for each location and whether a course of that CourseId/AwardId combination was available. There would be now rows for course/award combinations that have no offerings.

The required result, from the sample data, would be a recordset like this:

CourseId | CourseName | AwardId | AwardName | LocationA | LocationB | LocationC
---------+------------+---------+-----------+-----------+-----------+----------
1        | Course A   | 1       | Award A   | True      | True      | True
1        | Course A   | 2       | Award B   | True      | NULL      | NULL
2        | Course B   | 1       | Award A   | NULL      | NULL      | True

(NULL could also be False)

At present I am doing a simple SELECT statement with various JOINS which gives me multiple rows for each course/award combination, then I loop through all rows in my code and build the required result. However, I don’t think this is so efficient as I also need to page results.

I think I could do this fairly easily in a stored procedure by creating a temporary table and a bunch of separate queries, but I don’t think that would be too efficient. Wondering if there is a better way of doing it in T-SQL???

So to clarify, what I am looking for is a T-SQL query or stored procedure that will produce the above sample recordset, and which I could adapt paging to.

NB. I am using SQL Server 2008

Answer 1

For Dynamic columns:

DECLARE  @COLUMNS VARCHAR(max)
        ,@query varchar(1024)
        ,@True varchar(6)


SELECT @COLUMNS = 
COALESCE(
@Columns + ',[' + L.LocationName + ']',
'[' + L.LocationName +']'
)
FROM tblLocation L

SELECT @True = '''True'''

SELECT @QUERY = 'SELECT C.CourseName
                 ,A.AwardName
                 , pvt.*
FROM (SELECT O.OfferingID AS OID
            ,O.AwardID AS AID
            ,O.CourseID AS CID
            ,L.LocationName AS LID
       FROM tblOffering O Inner Join tblLocation L on L.LocationID = O.LocationID) AS S
PIVOT
(
    count(oID) For LID IN (' +@COLUMNS+ ')
) As pvt
inner join tblCourse C on C.CourseID = CID
inner join tblAward A on A.AwardID = pvt.AID'

EXEC (@QUERY)
GO