Comparing DateTime in Entity Framework with an Sql

问题:

Why this code throws a System.NotSupportedException telling that The specified method 'int? DateDiff(string, DateTime?, DateTime?)' on the type 'System.Data.Objects.SqlClient.SqlFunctions' cannot be translated into a LINQ to Entities store expression, though DateDiff has EdmFunction attribute?

context.Users.Where(f => System.Data.Objects.SqlClient.SqlFunctions.DateDiff("second", f.LastLogOn, somedatetime) < 0)

回答1:

Here is a complete enumeration of canonical Date and Time functions supported by Entity SQL query provider link.

Try something like this

context.Users.Where(f=>EntityFunctions.DiffSeconds(f.LastLogOn, somedatetime)<0);