Custom query assistance needed - sql

Question

I have 3 tables: (simplified for this question)
REQUIREMENTS : ID (PK), RequirementDescription
CUSTOMERS : ID (PK), CustomerName
CUSTOMER_REQUIREMENTS (join table): ID (PK), RequirementID (FK to REQUIREMENTS table), CustomerID (FK to CUSTOMERS table), DateCompleted
Question: I need to make a gridview in asp.net that basically shows the requirements on the left, all the customers as column headings and the DateCompleted as the "intersection". How can I do this?
For example:

Answer 1

Try following sql and replace temp tables with your table:
CREATE TABLE #REQUIREMENTS
(
ID INT,
RequirementDescription VARCHAR(100)
)
CREATE TABLE #CUSTOMERS
(
ID INT,
CustomerName VARCHAR(100)
)
CREATE TABLE #CUSTOMER_REQUIREMENTS
(
ID INT,
RequirementID INT,
CustomerID INT,
DateCompleted DATE
)
INSERT INTO #REQUIREMENTS VALUES (1,'Requirement1')
INSERT INTO #REQUIREMENTS VALUES (2,'Requirement2')
INSERT INTO #REQUIREMENTS VALUES (3,'Requirement3')
INSERT INTO #REQUIREMENTS VALUES (4,'Requirement4')
INSERT INTO #CUSTOMERS VALUES (1,'JOHN')
INSERT INTO #CUSTOMERS VALUES (2,'MARY')
INSERT INTO #CUSTOMERS VALUES (3,'BOB')
INSERT INTO #CUSTOMER_REQUIREMENTS VALUES (1,1,1,'2-2-2014')
INSERT INTO #CUSTOMER_REQUIREMENTS VALUES (1,2,1,'2-2-2014')
INSERT INTO #CUSTOMER_REQUIREMENTS VALUES (1,1,2,'2-2-2014')
INSERT INTO #CUSTOMER_REQUIREMENTS VALUES (1,2,2,'2-2-2014')
INSERT INTO #CUSTOMER_REQUIREMENTS VALUES (1,3,2,'2-2-2014')
INSERT INTO #CUSTOMER_REQUIREMENTS VALUES (1,4,2,'2-2-2014')
DECLARE #DynamicPivotQuery AS NVARCHAR(MAX)
DECLARE #ColumnName AS NVARCHAR(MAX)
SELECT #ColumnName= ISNULL(#ColumnName + ',','') + QUOTENAME(CustomerName) FROM (SELECT DISTINCT CustomerName FROM #CUSTOMERS) AS Courses
SET #DynamicPivotQuery =
N'SELECT ReqID, ReqDes, ' + #ColumnName + '
FROM
(
SELECT
TEMP.ReqID,
TEMP.ReqDes,
TEMP.CusName,
CusReq.DateCompleted
FROM
(
SELECT
req.ID as ReqID,
req.RequirementDescription as ReqDes,
cus.ID as CusID,
cus.CustomerName as CusName
FROM
#REQUIREMENTS req,#CUSTOMERS cus
) AS TEMP
LEFT JOIN
#CUSTOMER_REQUIREMENTS as CusReq
ON
TEMP.ReqID = CusReq.RequirementID AND
Temp.CusID = CusReq.CustomerID
) AS TEMP1
PIVOT(MAX(TEMP1.DateCompleted)
FOR CusName IN (' + #ColumnName + ')) AS PVTTable'
EXEC sp_executesql #DynamicPivotQuery
DROP TABLE #CUSTOMER_REQUIREMENTS
DROP TABLE #CUSTOMERS
DROP TABLE #REQUIREMENTS