Performing a join using LINQ

So what do you do when you’re using the nifty new ’entity framework’ and you’re getting data back with LINQ queries and you’ve reached the point where you want to get data back based on criteria in a related table?

Well, if you’re not using a stored proc to do it for you – you’ve got to do a join.

The join syntax in LINQ is similar to SQL syntax, but not quite the same.

Given the following relationships in the database…

… the join would look something like this:

var shoppingLists = from user in Users
								join listUsers in ShoppingListUsers
									on user.UserId equals listUsers.UserId
								join lists in ShoppingLists
									on listUsers.ShoppingListId equals lists.ShoppingListId
								where user.UserId == userToFind.UserId
								select lists;

return shoppingLists;