Question

Sorry, I couldn’t think of a better title! 🙂

I have a table called Process, and it has a recursive relationship to define Process-*Subprocess

Now, each Process can have one or more metrics attached to it: Process-*Metric

So my Process table would look like:

PROCESS
-------
ID
PID (fkey on Process.ID)

And my metric table would look like:

METRIC
------
ID
PID (fkey on Process.ID)

Using LINQ with EF, can I build a query that will return the sum of:

• the count of Metrics associated with a Process
• the count of Metrics associated with all Subprocesses that are descendents of that Process

I’m looking for a way to return this info with a single call to the db if possible.

Thanks!

Chris

Answer 1

Basically you have two options.

1. Read both tables into memory and process the result in code. Suitable for small collections.
2. Create a view with a recursive CTE and map that view in EF. Join with that view. More complicated to write, but gives the best performance, especially for large collections.