SQL Pivot Using three tables - sql-server

Question

I am running into some trouble trying to pivot some data out of SQL.
I have three tables that will comprise the data.
Table 1: (Clause)
-Clause
-ClauseName
Table 2: (Process)
-Id
-ProcessName
Table 3: (RELProcessClauses)
-ProcessId
-Clause
-WeightedValue
Ultimately, I am looking to have a matrix of data that is Clause, ClauseName down the left, ProcessName across the top and the Weighted value to correspond between Process and Clause.
Not sure if this will make much sense.

Answer 1

Join the three tables and use PIVOT on it. You can run the following query:
SELECT * FROM (
SELECT
c.Clause,
c.ClauseName,
p.ProcessName,
pc.WeightedValue
from RELProcessClauses pc
JOIN Clause c on pc.clause = c.clause
JOIN Process p on pc.ProcessId = p.id
) x
PIVOT (
SUM(WeightedValue)
FOR ProcessName IN ([ProcessName1], [ProcessName2], [ProcessName3])
) as pvt
Output table:
+--------+-------------+--------------+--------------+--------------+
| Clause | ClauseName | ProcessName1 | ProcessName2 | ProcessName3 |
+--------+-------------+--------------+--------------+--------------+
| 1 | ClauseName1 | 10 | 15 | 30 |
| 2 | ClauseName2 | 15 | 20 | 30 |
| 3 | ClauseName3 | 20 | 20 | 30 |
+--------+-------------+--------------+--------------+--------------+
The query/output works on the demo tables created using the query below:
CREATE TABLE Clause (
Clause int,
ClauseName varchar(255)
);
CREATE TABLE Process (
Id int,
ProcessName varchar(255)
);
CREATE TABLE RELProcessClauses (
ProcessId int,
Clause int,
WeightedValue int
);
INSERT INTO Clause VALUES
(1, 'ClauseName1'),
(2, 'ClauseName2'),
(3, 'ClauseName3');
INSERT INTO Process VALUES
(1, 'ProcessName1'),
(2, 'ProcessName2'),
(3, 'ProcessName3');
INSERT INTO RELProcessClauses VALUES
(1, 1, 10),
(1, 2, 15),
(1, 3, 20),
(2, 1, 15),
(2, 2, 20),
(2, 3, 20),
(3, 1, 30),
(3, 2, 30),
(3, 3, 30);