CurFrom CurTo FromDate ToDate ExcRate
BD AED 1/11/2006 5/11/2006 3.000
BD AED 6/11/2006 9/11/2006 3.120
BD AED 10/11/2006 15/11/2006 3.060
BD AED 16/11/2006 20/11/2006 3.010
BD AED 21/11/2006 null 3.020
1) Primary Key is CurFrom, CurTo, FromDate.So it cannot be updated.
But New records can be inserted. Old records can be deleted.
2) Todate can be null,
2) Date Range has to be always continous when ever a new record is inserted or deleted.
3) if date overlaps during insert or updates existing overlap
dates shud be updated accordingly, so that no overlap is present
4)if i try to insert a new record
a) BD - AED 1/11/2006 - 26/11/2006 5.000 - all the above records are in overlap
so the table shud look like (delete rec 2,3,4)
BD - AED 1/11/2006 - 26/11/2006 5.000
BD - AED 27/11/2006 - null 3.000 - (last record)
b) Continuity of the date range has to be maintained.