MS ACCESS Cross table DATA - sql

Question

I have two tables, one with employee details looks like this
Employee ID | Employee Name | Start Date | Termination Date |
2234 | John Smith | 2014-01-03 | |
3333 | Jane Doe | 2014-04-22 | 2014-10-31 |
1234 | Bobby Wilson | 2013-12-10 | |
My second table has there sales by month-year
looks like so
Employee ID | 2013-12 | 2014-01 | 2014-02 | 2014-03 | 2014-04 | etc | etc
2234 | | 199.99 | 130.00 | 300.00 | 230.99 | etc | etc
3333 | | | | | 204.02 | etc | etc
1234 | 455.99 | 332.32 | 334.00 | 553.00 | 334.99 | etc | etc
So what i need is to make a new Query that helps me show the trend of the employee on how their first month employeed sales number looks like, second month sales, third moneth sales etc. based on when the month one being when the employee started. Over a spand of 12 month or more
So the new table would look as follows
Employee | Month 1 | Month 2 | Month 3 | Month 4 | etc | etc |
2234 | 199.99 | 130.00 | 300.00 | 230.99 | etc | etc |
3333 | 240.02 | (month 2) | (month 3)| (month 4)| etc | etc |
1234 | 455.99 | 332.32 | 334.00 | 553.00 | etc | etc |
So I know we can join the two tables by Employee ID
and I know we can determine an employee's month one based on their start date
but how do you write this query out in SQL?

Answer 1

As i mentioned in my comment to the question, you need to change the design of your second table as follow (pseudo-code):
CREATE TABLE Sales(
SaleId Autonumber PK
[Employee ID] FK (reference to Employees table)
SalesDate DateTime
Sales Decimal/Double
);
Then you'll be able to save your data this way:
SaleID EmpId SalesDate Sales
1 2234 2014-01-01 199,99
2 1234 2013-12-01 455.99
3 1234 2014-01-01 332.32
4 2234 2014-02-01 130
5 1234 2014-02-01 334
6 2234 2014-03-01 300
7 1234 2014-03-01 553
8 2234 2014-04-01 230.99
9 3333 2014-04-01 204.02
10 1234 2014-04-01 334.99
Finally, your pivot table might look like:
TRANSFORM Sum(S.Sales) AS SumOfSales
SELECT E.[Employee Id], E.[Employee Name]
FROM Employees AS E INNER JOIN SalesByMY AS S
ON E.[Employee Id] = S.[Employee Id]
GROUP BY E.[Employee Id], E.[Employee Name]
PIVOT 'Month-' & DateDiff('m',[E].[StartDate],[S].[SalesDate])+1;
The result:
EmpId EmpName Month-1 Month-2 Month-3 Month-4 Month-5
1234 Bobby Wilson 455.99 332.32 334 553 334.99
2234 John Smith 199.99 130 300 230.99
3333 Jane Doe 204.02