Selgitage, mis on INCLUDE operaator SQL-is ja kuidas seda kasutatakse päringutes

In SQL, the INCLUDE statement does not exist directly, but in the ORM context, for example in C# with Entity Framework, Include is a method for eager loading related entities.

It is used to immediately load related data when selecting the main entity, preventing the "N+1 query" problem.

Example of usage in Entity Framework:

var orders = context.Orders
    .Include(o => o.Customer)  // loads related Customer data along with Orders
    .ToList();

Here, Include indicates that when selecting orders, related customer information should also be loaded.

This helps optimize queries and avoid additional database calls when working with navigation properties.