Data Cogs Information Technology

Does this date range overlap that date range?  Use this T-SQL function to find out.

UPDATE:  There is a far simpler way to do this.  It turns out all the cases in the above example can be handled by the one condition:

If @StartDate1 <= @EndDate2 AND @StartDate1 <= @EndDate1 then the date ranges overlap.  See full example below:

/*************************************************************
--Purpose:      Returns 1 is two date ranges overlap, 0 if they don't
--
--Created By: Mark Daunt
--Example Usage:
 SELECT dbo.fnOverlaps('20040101', '20040630', '20040615', '20050101')

**************************************************************
--Handles the following cases of overlapping date ranges
 |---------|
  S1        E1

        |----|
       S2   E2

|---------|
S1       E1

        |------------|
      S2           E2

|---------|
S1        E1

    |----|
  S2   E2

 |---------|
 S1        E1

    |---------|
   S2        E2

 |---------|
 S1        E1

    |--------------|
    S2             E2
*/
CREATE   FUNCTION dbo.fnOverlaps
(
 @StartDate1 DATETIME,
 @EndDate1 DATETIME,
 @StartDate2 DATETIME,
 @EndDate2 DATETIME
)
RETURNS BIT
AS BEGIN
 DECLARE @RetVal BIT
 IF  @StartDate1 <= @EndDate2 AND @StartDate1 <= @EndDate1
  SET @RetVal = 1
 ELSE
  SET @RetVal = 0
 RETURN @RetVal
END