Re: How should I initialize a header field from the sum of a detail field?

[Phillip Ward]

Sounds to me like you Architecture has already dictated your solution, regardless of what the "right way" might be.

For a pair of tables in a single database (which is what most people here are working with), what I suggested - on-demand derivation or triggers - is the "right way" to go.

What you actually have - but didn't mention - is a distributed system with separate tables in separate databases. There's very little that a purely "database" solution can offer you.

You're going to have to handle this at the Application layer with some kind of "reconciliation" process available for those times when it goes wrong (and, let's face it, it will).

Regards, Phill W.