C# linq use 3 tables

Question

In a C# 2008 application I have the following linq to sql statement setup so far. eDataContext eData = new eDataContext(); var eSelect = (from iw in eData.Ibooks join ip in etData.IPack on iw.P_ID equals ip.P_ID join eTrack in eData.eRPT_Trans on ip.TNum equals eTrack.P_ID where ip.TNum == packageId select iw).FirstOrDefault(); I want to obtain values from the 3 different tables listed in the statement aove. How do I change the linq statement above so that I can obtain data from all three tables? Thus can you show me how to obtain data from all 3 tables?

Vulpes · Answer

You have to select an 'anonymous type' consisting of columns from the three tables. For example suppose the Ibooks IPack and eRPT_Trans tables have respective columns called Col1 (string) Col2 (double) and Col3 (int) where you want to retrieve the first instance which satisfies the filter or null if there are no instances. Then you could do it like this: var eSelect = (from iw in eData.Ibooks join ip in etData.IPack on iw.P_ID equals ip.P_ID join eTrack in eData.eRPT_Trans on ip.TNum equals eTrack.P_ID where ip.TNum == packageId select new{Col1 = iw.Col1 Col2 = ip.Col2 Col3 = eTrack.Col3} ).FirstOrDefault(); if (eSelect != null) { string s = eSelect.Col1; double d = eSelect.Col2; int i = eSelect.Col3; //.... }