>>>The meter reading is identifyed by the AssetId field. All tables that relate to equipment use the AssetId field as the relation. I have a seperate meter reading table that has the AssetId and date and the meter reading for each time the meters are read.
>>>
>>>Are you saying that I could have a seperate field for meter adjustments in the equipment table and that I add or subtract (as needed) the value in the meter adjustment field??? Sounds good to me as I think about it. So if the meter adjustment field is 0 (ie. the meter has never been replaced) the calculations do nothing... If there is a value there then if I need total hours I add that value to the current reading... What do you think?
>>>
>>>Thanks
>>
>>That sounds fine - as long as you allow for more than one "breakage" some how if necessary.
>>My point was essentially that when things get complex like this, as they always do in real life, a simple table structure rarely copes - a separate date/time-based table for the meters themselves will give you a basis for doing more accurate calculations, and give you a history of your meters.
>>Regards
>
>Hi David,
>
>I don't think that I understand what you mean by a separate date/time based table for the meters? Can you re-describe that? I have a table that records each time the meter is read along with the date/time of the reading.
>
>Thanks

Oh - I just meant a table like:
Meterid
Location
DatetimeInstalled
Startreading
Endreading
DatetimeRemoved

where meterid and location form the primary key. So a meter could be re-used after servicing perhaps.

depends on whether you need this sort of info and how it fits in with your data model.
HTH