Query logic issue: Using parameters and variables in a single query - sql

Question

I'm trying to combine 2 different select statements (each are being put into 2 variables) and then using 2 parameters to show my results, but I'm not 100% confident with my logic.
I'm using 2 tables (Salaries and Department)
I first created the procedure with the 2 parameters:
CREATE PROCEDURE DepartmentPercentage
(
#Dept VARCHAR(20)
#DeptPercent int OUTPUT
)
Then I declared and set my 2 variables, using an inner join in one of them to connect the Salaries and Department tables:
AS
DECLARE #Sal int
DECLARE #DeptRate int
SET #Sal = (SELECT SUM(AN_RATE) FROM Salaries) --Total Annual Rate for the entire table
SET #DeptRate = (SELECT SUM(S.AN_RATE) -- Calculates the Total Annual Rate for a given Department
FROM Salaries as S
INNER JOIN Department as D
ON D.DEPT_ID = S.DEPT_ID
WHERE DESCRIPTION = #Dept)
Then I put my out parameter to equal a division between the 2 declared variables:
#DeptPercent = (#DeptRate/#Sal)
My execution statement:
EXEC DepartmentPercentage #Dept = 'Fire Department', #DeptPercent;
Any help with my logic would be much appreciated. I don't know too much about using multiple parameters and variables in a single query.

Answer 1

This should get you Close to the results you want without the need for all the parameters and variables:
SELECT SUM(S.AN_RATE) AS total,
SUM(CASE DESCRIPTION WHEN #Dept THEN S.AN_RATE ELSE 0 END) AS dept,
SUM(CASE DESCRIPTION WHEN #Dept THEN S.AN_RATE ELSE 0 END) / SUM(S.AN_RATE) AS deptPercent
FROM Salaries as S
INNER JOIN Department as D
ON D.DEPT_ID = S.DEPT_ID
I know you probably only want the last column but thought the other 2 might help other people. If I get chance in the morning I'll setup a SQLfiddle with test data.
SQLFiddle seems to be having some problems at the minute so here is a worked example:
--Test Data Setup
DECLARE #Salaries AS TABLE (SAL_ID int, DEPT_ID int, AN_RATE decimal(7,2))
DECLARE #Department AS TABLE (DEPT_ID int, DEPT_DESCRIPTION VARCHAR(20))
INSERT INTO #Department VALUES (1, 'Fire Department')
INSERT INTO #Department VALUES (2, 'Earth Department')
INSERT INTO #Department VALUES (3, 'Wind Department')
INSERT INTO #Salaries VALUES (1, 1, 10000.00)
INSERT INTO #Salaries VALUES (2, 1, 15000.00)
INSERT INTO #Salaries VALUES (3, 1, 20000.00)
INSERT INTO #Salaries VALUES (4, 3, 25000.00)
INSERT INTO #Salaries VALUES (5, 2, 22000.00)
INSERT INTO #Salaries VALUES (6, 2, 21000.00)
--Parameter
DECLARE #Dept VARCHAR(20)
SET #Dept = 'Fire Department'
--Query
SELECT SUM(S.AN_RATE) AS total,
SUM(CASE DEPT_DESCRIPTION WHEN #Dept THEN S.AN_RATE ELSE 0 END) AS dept,
SUM(CASE DEPT_DESCRIPTION WHEN #Dept THEN S.AN_RATE ELSE 0 END) / SUM(S.AN_RATE) * 100 AS deptPercent
FROM #Salaries as S
INNER JOIN #Department as D
ON D.DEPT_ID = S.DEPT_ID