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Asked: 2026-06-10T05:35:54+00:00

I am getting to grips with LINQ and I’m stuck on the basic concepts

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I am getting to grips with LINQ and I’m stuck on the basic concepts and techniques of implementing a lookup table into objects and then querying that object (or it’s association). This may be a dumb question and probably has an answer that I should have worked out myself. But I have yet to find an explanation that has made the method stick.

So I have created an example DB structure like so

Example Database

and I would like to two LINQ queries the first that gives me all of the example2 records that are related via the lookup to a specified object1 and the second that gives me all the example1 records that are related to a specified object2

hope someone out there can kick start my brain.

something like 

var examples = (from e in db.examples where e.example2.id == id).ToList();

SQL Query written quickly

SELECT * FROM [dbo].[example1] one
JOIN [dbo].[examplelookup] lu ON one.[id] = lu.[example1id]
JOIN [dbo].[example2] two ON lu.[example2id] = two.[id]
WHERE one.[id] = 1

Just nipped off and created this which I think should explain a bit more

model

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1 Answer

  1. Editorial Team

    Assuming

    example1-> examplelookup relation name is examplelookups

    example2-> examplelookup relation name is examplelookups

    examplelookup -> example1 relation name is example1

    examplelookup -> example2 relation name is example2

    given id of example1

    db.example1.Where(x=>x.id == id).SelectMany(x=>x.examplelookups).Select(x=>x.example2);

    and visa versa

    db.example2.Where(x=>x.id == id).SelectMany(x=>x.examplelookups).Select(x=>x.example1);

    EDIT: Additional update based on Gert Arnold’s suggested answer to use the any clause (this is after already accepted as an answer)

    db.example1.Where(x=>x.examplelookups.Any(y=>y.example2.id == id));

    and visa versa

    db.example2.Where(x=>x.examplelookups.Any(y=>y.example1.id == id));

    2nd Edit (again after already accepted and answer but after the question was modded to include the data model)

    db.Example1.Where(x=>x.Id == id).SelectMany(x=>x.Example2); // could have duplicates
db.Example2.Where(x=>x.Example1.Any(y=>y.Id == id)); //alternate any form removing the duplicates

    and visa versa

    db.Example2.Where(x=>x.Id == id).SelectMany(x=>x.Example1); // could have duplicates
db.Example1.Where(x=>x.Example2.Any(y=>y.Id == id)); //alternate any form removing the duplicates
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