Grouping SQL columns from one table - sql-server

Question

I am currently having difficulty getting the correct values from my table. Here is my table
NOTE: The column Status has 3 possible values (Cleaned, Unclean, Closed)
+-----------+-------------+--------+------------+
|ApplicantID|ApplicantName| Status | HireDate |
+-----------+-------------+--------+------------+
| 1 | John Smith |Cleaned |08/26/2015 |
| 2 | Alex Murphy |Closed |09/12/2015 |
| 3 | Oliver David|Cleaned |01/11/2015 |
| 4 | Max Payne |Unclean |03/18/2015 |
+-----------+-------------+--------+------------+
The output I'm expecting and it should also be sorted by year.
For example I call all these records for the year 2015 which I get using the variable #Year.
NOTE: The column Total is the SUM of Cleaned and Unclean
+---------+-----------+-----------+----------+---------+
| Month | Cleaned | Unclean | Closed | Total |
+---------+-----------+-----------+----------+---------+
| January| 1 | 0 | 0 | 1 |
| February| 0 | 0 | 0 | 0 |
| March | 0 | 1 | 0 | 1 |
| April | 0 | 0 | 0 | 0 |
| May | 0 | 0 | 0 | 0 |
| June | 0 | 0 | 0 | 0 |
| July | 0 | 0 | 0 | 0 |
| August | 1 | 0 | 0 | 1 |
|September| 0 | 0 | 1 | 0 |
| October| 0 | 0 | 0 | 0 |
| November| 0 | 0 | 0 | 0 |
| December| 0 | 0 | 0 | 0 |
+---------+-----------+-----------+----------+---------+
I can't seem to get the right code, for the sql this is my current code.
SELECT Month(HireDate) AS Month, COUNT(*)
FROM Hires
GROUP BY Month(HireDate)
I know my coding is wrong, because it is incomplete.

Answer 1

Generate a list of numbers from 1 to 12 first to hold all months. Then do a LEFT JOIN on Hires to make sure all missing months are accounted for. Then use conditional aggregation for the totals:
SQL Fiddle
;WITH CteMonths AS(
SELECT * FROM(VALUES
(1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(11),(12)
)t(N)
)
SELECT
Month = DATENAME(MONTH, DATEADD(MONTH, N-1,0)),
Cleaned = SUM(CASE WHEN h.Status = 'Cleaned' THEN 1 ELSE 0 END),
Closed = SUM(CASE WHEN h.Status = 'Closed' THEN 1 ELSE 0 END),
Unclean = SUM(CASE WHEN h.Status = 'Unclean' THEN 1 ELSE 0 END),
Total = SUM(CASE WHEN h.Status IN('Cleaned', 'Unclean') THEN 1 ELSE 0 END)
FROM CteMonths m
LEFT JOIN Hires h
ON m.N = MONTH(h.HireDate)
--AND YEAR(h.HireDate) = #year --uncomment this line to filter for year.
GROUP BY m.N
ORDER BY m.N
If you want to include the YEAR:
SQL Fiddle
;WITH CteMonths AS(
SELECT * FROM(VALUES
(1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(11),(12)
)t(N)
),
CteYears(yr) AS(
SELECT DISTINCT YEAR(HireDate) FROM Hires
),
CteAllDates(dt) AS(
SELECT
DATEADD(MONTH, m.N - 1, DATEADD(YEAR, y.yr - 1900, 0))
FROM CteMonths m
CROSS JOIN CteYears y
)
SELECT
Year = YEAR(d.dt),
Month = DATENAME(MONTH, d.dt),
Cleaned = SUM(CASE WHEN h.Status = 'Cleaned' THEN 1 ELSE 0 END),
Closed = SUM(CASE WHEN h.Status = 'Closed' THEN 1 ELSE 0 END),
Unclean = SUM(CASE WHEN h.Status = 'Unclean' THEN 1 ELSE 0 END),
Total = SUM(CASE WHEN h.Status IN('Cleaned', 'Unclean') THEN 1 ELSE 0 END)
FROM CteAllDates d
LEFT JOIN Hires h
ON MONTH(d.dt) = MONTH(h.HireDate)
AND YEAR(d.dt) = YEAR(h.HireDate)
GROUP BY YEAR(d.dt), MONTH(d.dt), DATENAME(MONTH, d.dt)
ORDER BY YEAR(d.dt), MONTH(d.dt)
If you want to filter for year, say #year = 2015, you can replace the previous ctes with:
;WITH CteMonths AS(
SELECT * FROM(VALUES
(1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(11),(12)
)t(N)
),
CteAllDates(dt) AS(
SELECT
DATEADD(MONTH, m.N - 1, DATEADD(YEAR, #year - 1900, 0))
FROM CteMonths m
)...

Answer 2

I suggest to create TEMP table with values from 1 to 12 (numbers of months) and JOIN your table with TEMP table. To achieve values as columns names you can use PIVOT or CASE. You can do It in following:
INSERT INTO #Months VALUES
(1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(11),(12)
SELECT DATENAME(MONTH, DATEADD(MONTH, m.Id-1, 0)) AS [Month]
, SUM(CASE WHEN [Status] = 'Cleaned' THEN 1 ELSE 0 END) AS [Cleaned]
, SUM(CASE WHEN [Status] = 'Closed' THEN 1 ELSE 0 END ) AS [Closed]
, SUM(CASE WHEN [Status] = 'Unclean' THEN 1 ELSE 0 END) AS [Unclean]
, SUM(CASE WHEN [Status] IN ('Unclean', 'Cleaned') THEN 1 ELSE 0 END) AS [Total]
FROM #Test t
RIGHT JOIN #Months m ON m.Id = MONTH(t.HireDate)
GROUP BY m.Id
OUTPUT
+---------+-----------+-----------+----------+---------+
| Month | Cleaned | Unclean | Closed | Total |
+---------+-----------+-----------+----------+---------+
| January | 1 | 0 | 0 | 1 |
| February| 0 | 0 | 0 | 0 |
| March | 0 | 1 | 0 | 1 |
| April | 0 | 0 | 0 | 0 |
| May | 0 | 0 | 0 | 0 |
| June | 0 | 0 | 0 | 0 |
| July | 0 | 0 | 0 | 0 |
| August | 1 | 0 | 0 | 1 |
|September| 0 | 0 | 1 | 0 |
| October | 0 | 0 | 0 | 0 |
| November| 0 | 0 | 0 | 0 |
| December| 0 | 0 | 0 | 0 |
+---------+-----------+-----------+----------+---------+
DEMO
You can test It at: SQL FIDDLE