How do I just LINQ Join() to link two IQueryables?

Question

I have two IQueryables:

Ingredient:

IngId
Description

AvailableIngredient:

IngId
         


        

Answer 1

Use the first query as the source of the subsequent query.

IQueryable query = from item in context.Ingredients
                             // Quite a few `where` clauses and stuff
                               select item;

if (filterByAvailable)
{
    IQueryable availableQuery = GetAvailableIngredientQuery(context);
    query = from item in query
            join t in availableQuery on item.IngId equals t.IngId
            select item;
}