How to Select records that don't exist in Sql Server

Question

This isn\'t about checking if a record exists before selecting it, or viceversa.

The issue is this, I have a database with many records, they are stored by date, by

Answer 1

Eric Fan had the right idea, but I thought it might help to see an implementation:

Here's a function that will return a table of the inclusive dates:

CREATE FUNCTION dbo.fDatesBetween(@startDate Date, @endDate Date)
    RETURNS @tbl TABLE
        (
            a_date      Date
        )
AS BEGIN
    DECLARE @thisDt Date
    SET @thisDt = @startDate

    WHILE @thisDt <= @endDate
    BEGIN
        INSERT INTO @tbl SELECT @thisDt
        SET @thisDt = DateAdd(day, 1, @thisDt)
    END
    RETURN
END

Now, if you do an outer join to your table from the function results, you will have what you are looking for:

SELECT DATES.a_date, SampleTable.value1, SampleTable.value2
  FROM dbo.fDatesBetween(@startDate, @endDate) DATES
       LEFT JOIN SampleTable
          ON DATES.a_date = SampleTable.dt

That should give you just what you asked for.