Question

this is my relational model:

  Request
  ------------------------------
  RequestId
  ------------------------------
  1
  2


  RequestState
  ------------------------------
  RequestStateId | Name
  ------------------------------
  10             | Received
  20             | Processing
  30             | Finsihed


  Request_RequestState
  -------------------------------------------------------------------
  Request_RequestStateId | RequestId | RequestStateId | CreatedOn
  -------------------------------------------------------------------
  1                      | 1         | 10             | 2010-01-01
  2                      | 1         | 20             | 2010-01-02
  3                      | 2         | 10             | 2010-01-15

Each time a request state changes, this change is stored.
Now I need to list requests by its current state.
Like “Get all requests with current state = Received”.

So far I only managed to created a query that return requests of a given state, but it doesn’t matter if it is the current state or an older one… So I somehow need to use CreatedOn to get the latest/current state.

Any help? Thanks in advance!

Answer 1

You change your model…

With the current scheme, as more and more data changes take place, it will take longer and longer to determine the current state using the queries suggested above…

You need a “Current_Request_State” attribute on your request.