How can I call local method in Linq to Entities query?

Question

I have the following code:

public void SalesCount(string customerId)
{
  ..
  ..
  return ...;
}

var resultQuery = dataContext.Customers
.Where (c => c.N         


        

Answer 1

Simply you can't. You can't execute C# code on the SQL server directly, you can use only Expressions and some special recognized functions...

Unless you transform your query (at least partially) in a LINQ-to-Objects...

var resultQuery = dataContext.Customers
    .Where (c => c.Name == "Alugili")
    .AsEnumerable()
    .Where (c => SalesCount(c.CustomerId) < 100);

Be aware that the last Where will be executed on the client side, so many useless rows will be fetched from the DB.