Write a SQL Query to replace values and include all the Dates - sql

Question

Well I have this -
Table DimDate- Date
Table Employee- Id,Name,Points,Date
Now the Employee table has points for everyday unless they did not come...so the Date does not have all the Dates entries... I mean for e.g in a week he did not come for 2 days the Employee table has only 5 rows...so I have this dimdate table which has all the dates till 2050 which I want to join with and add Zeros for the dates he does not have points. So I have written this query but does not work -
Select E.EmployeeId,D.Date,isNull(E.Points,0) from DimDate D left join Employee E on D.Date between '01-01-2009'and '06-01-2009' where E.EmployeeId=1
The above query give multiple dates and I tried group by on Date but does not work.

Answer 1

You probably dont want to join the two tables on a date range but a date. Then filter the record set by the date range. example
Select
E.EmployeeId,
D.Date,
isNull(E.Points,0)
from DimDate D
left join Employee E on D.Date = E.Date
where E.EmployeeId=1
AND D.Date Between '01-01-2009'and '06-01-2009'
Edited:
Select
E.EmployeeId,
D.Date,
isNull(E.Points,0)
from DimDate D
left join Employee E on D.Date = E.Date And E.EmployeeId=1
where D.Date Between '01-01-2009'and '06-01-2009'
OR
Select
E.EmployeeId,
D.Date,
isNull(E.Points,0)
from DimDate D
left join Employee E on D.Date = E.Date
where (E.EmployeeId = 1 OR E.EmployeeId is NULL)
AND D.Date Between '01-01-2009'and '06-01-2009'

Answer 2

I think you need a cross join between the dimdates table and the table where your employees are defined. This will give you a list of records with all employee/date combinations. Then the result of that needs to be left outer joined to the table that has the employee points records.
Something like:
Select CJ.EmployeeId,CJ.Date,isNull(E.Points,0)
from (SELECT EmployeeID, D.Date
from DimDate D CROSS JOIN [EmployeeDefinitionTable] as edt) as CJ
left outer join Employee E on CJ.Date =E.Date AND CJ.EmployeeId = E.EmployeeId
where CJ.Date between '01-01-2009'and '06-01-2009'
and E.EmployeeId = 1
Where EmployeeDefinitionTable is a table that uniquely lists all employees (or at least their id's for this problem statement).
This also captures employees with no points entries.
The between statement and/or EmployeeId filtering could be moved up into the cross join if it fits your requirements. It would make the cross join more efficient.