Calculating Year to Date Total - sql-server

Question

I want to generate a Payroll type query whereby the values in Payroll 1 (say for the previous month) should be included in Payroll 2 (for the current month) Year-to-Date Totals.
This can best be explained with an example:
DECLARE #MyTable TABLE(ID INT IDENTITY, PayrollID INT, Description NVARCHAR(MAX), [Current Month] MONEY)
INSERT INTO #MyTable
VALUES (1,'Basic Salary',100),
(1,'Normal Over Time',50),
(1,'Work on Saturday',150),
(1,'Work on Sunday',200),
(2,'Basic Salary',100)
SELECT * ,SUM([Current Month]) OVER (PARTITION BY Description ORDER BY PayrollID) AS [Month to Date]
FROM #MyTable
When I run the above I get
ID EmployeeID PayrollID Description Current Month Month to Date
1 1 1 Basic Salary 100 100
2 1 1 Normal Over Time 50 50
3 1 1 Work on Saturday 150 150
4 1 1 Work on Sunday 200 200
5 1 2 Basic Salary 100 200
The Year-to-Date running totals are per each Description meaning Basic Salary Category has its own running total and so does Saturday and Sunday etc, etc. You will notice that for Basic Salary in Payroll 2 the running Year-to-Date total is 200 (i.e. 100 from Payroll 1 + 100 from Payroll 2)
The challenge I have is that Payroll 1 has data for Basic Salary, Work on Saturday and Work on Sunday whereas Payroll 2 only has Basic Salary as the employee did not work on Saturday nor on Sunday in Payroll 2 (the current month).
However, in the cumulative Year-to-Date column the data from Payroll 1 (previous month) should still be selected and included in the Year-to-Date running Total -
something like this:
ID EmployeeID PayrollID Description Current Month Month to Date
1 1 1 Basic Salary 100 100
2 1 1 Normal Over Time 50 50
3 1 1 Work on Saturday 150 150
4 1 1 Work on Sunday 200 200
5 1 2 Basic Salary 100 200
2 1 1 Normal Over Time NULL 50
3 1 1 Work on Saturday NULL 150
4 1 1 Work on Sunday NULL 200
Although the employee did not work on Saturday nor Sunday in the current month (Payroll 2) the running (Year-to-Date) totals for working on a Saturday should be 150 that he/she worked in the previous month (Payroll 1). The same should apply to working on Sunday where the running total in the current month (Payroll 2) should be the 200 that he/she worked in the previous month (Payroll 1).
How do I do that with a simple Select Statement without writing a complicated Procedure?
EDIT:
I have cleaned up the ode as follows:
DECLARE #MyTable TABLE(ID INT IDENTITY, EmployeeID INT, PayrollID INT, Description NVARCHAR(MAX), [Current Month] MONEY)
INSERT INTO #MyTable
VALUES (1,1,'Basic Salary',100),
(1,1,'Normal Over Time',50),
(1,1,'Work on Saturday',150),
(1,1,'Work on Sunday',200),
(1,2,'Basic Salary',100)
WITH pay_elements AS
(
SELECT Description
FROM #MyTable
GROUP BY Description
)
,pay_slips AS
(
SELECT EmployeeID, PayrollID
FROM #MyTable
GROUP BY EmployeeID, PayrollID
)
,pay_lines AS
(
SELECT
mt.ID
,PS.EmployeeID
,PS.PayrollID
,PE.Description
,ISNULL(mt.[Current Month], 0) AS [Current Month]
FROM
pay_slips AS ps
OUTER APPLY
pay_elements AS pe
LEFT JOIN
#MyTable AS mt
ON (mt.EmployeeID = ps.EmployeeID)
AND (mt.PayrollID = ps.PayrollID)
AND (mt.Description = pe.Description)
)
SELECT * ,SUM([Current Month]) OVER (PARTITION BY EmployeeID, Description ORDER BY PayrollID) AS [Month to Date]
FROM pay_lines
And I get this error:
Msg 319, Level 15, State 1, Line 10
Incorrect syntax near the keyword 'with'. If this statement is a common table expression, an xmlnamespaces clause or a change tracking context clause, the previous statement must be terminated with a semicolon.
Msg 102, Level 15, State 1, Line 17
Incorrect syntax near ','.
Msg 102, Level 15, State 1, Line 23
Incorrect syntax near ','.

Answer 1

You first need to build a "structure" of row headings, and then join that onto the actual data.
So for example:
WITH pay_elements AS
(
SELECT Description
FROM #MyTable
GROUP BY Description
)
,pay_slips AS
(
SELECT EmployeeID, PayrollID
FROM #MyTable
GROUP BY EmployeeID, PayrollID
)
,pay_lines AS
(
SELECT
mt.ID
,pay_slips.EmployeeID
,pay_slips.PayrollID
,pay_elements.Description
,ISNULL(mt.Current_Month, 0) AS Current_Month
FROM
pay_slips AS ps
OUTER APPLY
pay_elements AS pe
LEFT JOIN
#MyTable AS mt
ON (mt.EmployeeID = ps.EmployeeID)
AND (mt.PayrollID = ps.PayrollID)
AND (mt.Description = pe.Description)
)
SELECT * ,SUM([Current Month]) OVER (PARTITION BY EmployeeID, Description ORDER BY PayrollID) AS [Month to Date]
FROM pay_lines
What we're doing here is getting a list of the different kind of pay elements in your table. Then we're getting a list of Employees and Payrolls done to date, and manually forcing every Payroll to include a row in respect of all possible pay elements.
Once that structure is built, we join onto the base table to get the actual values (replacing NULLs with zeros, for those pay elements that weren't originally included in the base table).
Then we simply query this padded-out table in the same way you did originally.
Note, I've written this on the fly and haven't checked this code so please excuse any minor errors.

Answer 2

I am little confused with the column you mentioned Year-to-Date in your description. I assume this might be [Month to Date] column present in your query. Please correct me if I am wrong.
I think what you are trying to achieve is - the descriptions which are not present in payroll ID 2 like Work on Saturday and Work on Sunday should also be selected below the result set.
Problem is:
Summation of NULL value is always NULL so if [Current Month] value is NULL then you can not achieve to display 50,150,200 in the [Month to Date] column
You can have fixed categories against each payroll id:
Normal Over Time
Work on Saturday
Work on Sunday
Basic Salary
Query:
DECLARE #MyTable TABLE(ID INT IDENTITY, PayrollID INT, Description NVARCHAR(MAX), [Current Month] MONEY)
INSERT INTO #MyTable
VALUES (1,'Basic Salary',100),
(1,'Normal Over Time',50),
(1,'Work on Saturday',150),
(1,'Work on Sunday',200),
(2,'Basic Salary',100),
(2,'Normal Over Time',0),
(2,'Work on Saturday',0),
(2,'Work on Sunday',0)
SELECT * ,SUM([Current Month]) OVER (PARTITION BY Description ORDER BY PayrollID) AS [Month to Date]
FROM #MyTable order by ID,PayrollID