History problem

  • Thread starter Thread starter Guest
  • Start date Start date
G

Guest

Items have a location on a Track.
Items have events happen to them such as assessment, re-assessment, repairs,
reitrement.
Items have Parameters and Values for Parameters.

The tables are shown below. What I need is to always be able to show the
current values for each item and keep a history record. I know that to keep
the history I add a field called Updated, and when a change happens to an
Item, a tick goes in the Updated field, and Items with Updated = True, do not
appear in the current records.

To which table do I add the field Updated?
How do I differentiate between initial assessment which is an Event for
which Updated = False, without users knowing that there is a distinction
between initial assessment and next month or year when the Item is
re-assessed.

Users work at a very basic level and only want to enter assessments or
repairs, not to have to decide if this is an initial assessment or a
re-assessment. This is confusing for me because Updated = True for
re-assessment, repair and retirement.

A repair is a type of re-assessment because Values of Parameters of Items
change. An Item is retired when it is removed, not replaced and disappears
from the current records.

New Items can be installed where there was no previously existing item
during a repair Event or for some other reason, so the Values for the new
Item become the initial assessment not a re-assessment.

Tracks
TrackID
Track name

Items
ItemID

Events
EventID
ItemID <<<link to Items 1:m
Date
EventDescription (assessment, repair, retirement, re-assessment)
Cost estimate
Actual cost

Parameters
ParameterID
Parameter description

Values
ValueID
ItemID <<<link to Items 1:m
ParameterID <<<link to Parameters 1:m
 
I have worked out for myself where to put the fiels Updated. I have make
slight change to tables. I would welcome any comments if there any flaws in
this design.


Tracks
TrackID
Track name
<other info>

ItemTrack
ItemID
TrackID <<<link to Tracks 1:m
ItemName

EventType
EventTypeID (assessment, repair, retirement)

Events
EventID
EventTypeID <<<link to Events 1:m
ItemID <<<link to Items 1:m
Date
RepairDescription
Cost estimate
Actual cost
Updated

Values
ItemID <<<link to Items 1:m
ParameterID <<<link to Parameters 1:m
Date
TextValue
NumValue

Parameters
ParameterID
Parameter description
 

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