Question

I have two variables containing dates. DateStart and DateEnd (in SQL).
I also have two DatePicker controls (in a WinForm).
I import the two dates from the database and need to do something tricky.

So the two variables create a range of dates and the two date pickers create another range of date.
How can I check if these dates range are overlapping with a Sql query ?

E.g (yyyy/mm/dd format)

DateStart = 2012/07/01, DateEnd = 2012/07/31

| DatePicker1  | DatePicker2 | Overlapping | 
--------------------------------------------
| 2012/07/15   | 2012/07/16  |    True     |
--------------------------------------------
| 2012/07/31   | 2012/08/01  |    True     |
--------------------------------------------
| 2012/06/20   | 2012/07/01  |    True     |
--------------------------------------------
| 2012/08/01   | 2012/09/01  |    False    |
--------------------------------------------

I know it’s a little messed up but I didn’t know how else to ask this.

Answer 1

Two date ranges overlap if start of first range is before end of second range and end of first range is after start of second range. So:

where DateStart <= @DatePicker2
  and DateEnd >= @DatePicker1

A good explanation is this way.