To retrieve results from multiple tables using LINQ, you can use the Join operator. The Join operator takes two or more tables as input and returns a new table that contains the rows from all the tables that match the join condition.

The join operator has the following syntax:

from table1 in source
join table2 in otherSource on table1.column1 equals table2.column2
select new { column1, column2 }

where source is the name of the first table, otherSource is the name of his second table, column1 is the name of the column in the first table that is used to join the tables, and column2 is the name of the columns of the second table that is used to join the tables.

For example, the following code joins the Customers and Orders tables:

from customer in Customers
join order in Orders on customer.Id equals order.CustomerId
select new { customer.Name, order.OrderId }

This code returns a new table that containing the names of all the customers and the IDs of all orders.

You can also join three or more tables using the Join operator. For example, the following code joins the Customers, Orders, and Products tables:

from customer in Customers
join order in Orders on customer.Id equals order.CustomerId
join product in Products on order.ProductId equals product.Id
select new { customer.Name, order.OrderId, product.Name }

This code returns a new table containing the name of all customers, the IDs of all orders, and the names of all the products that they ordered.