Question

Lets say I have something like this in my database (abstract)

MyTable {
  Long ID Primary Key NOT NULL,
  Date ValidFrom Primary Key NOT NULL,
  Date ValidTo
}

Basically an Entity with Composite primary key on ID and ValidFrom. Now I have some date range for example 2012-09-01 -> 2012-09-30.

My question is: can I made smart hibernate query, which on repeated ID, but different ValidFrom key, return this one with latest date?

For example data:

Row 1 {
  Long ID = 1,
  Date ValidFrom 2012-09-01,
  Date ValidTo 2012-09-15 
}

Row2 {
  Long ID = 2,
  Date ValidFrom 2012-09-01,
  Date ValidTo 2012-09-15 
}

Row3 {
  Long ID = 1,
  Date ValidFrom 2012-09-16,
  Date ValidTo null
}

Selecting those rows which are between given date (2012-09-01 -> 2012-09-30) would return only Row2 and Row3 (as Row1 and Row3 havee same ID, so we get latest).

Is there any query(criteria API?) or do I need to take all entries and then filter with some method?

Answer 1

I ended it with making request for are Rows and then taking latest with

Collections.max(...)

With Date comparator