DECLARE  @StartDate datetime = '6/1/2015',
        @EndDate datetime = '6/30/2015'

DECLARE @DayRange int = (select DateDiff(day,@StartDate,@EndDate))

--This can be done differently, I made this negative
SET @DayRange = - @DayRange

--This is your temp table that will have all your dates in the range
DECLARE @Temp Table
(
ID int IDENTITY(1,1),
DataDate DateTime,
DataValue int
)

--Fill the temp table with all the dates
WHILE(@DayRange < 1)
BEGIN
INSERT INTO @Temp
SELECT DateAdd(day,@DayRange,@EndDate),0
SET @DayRange = @DayRange + 1
END

--Check out your temp table
SELECT * FROM @Temp