Support CommonTable Expressions

[glatzert]

If you are working with trees and hierarchies, which are materialized into a SQL Server, it would be good to have a possibility of defining recursive CommonTable Expressions (as defined here: https://msdn.microsoft.com/de-de/library/ms175972.aspx).

My proposal for that: an extension method for DbContext, which returns a IQueryable:

public class MyContext : DbContext {
    public IQueryable<ComplexType> MyCTE { 
        get {
            return this.RecursiveQuery(AnchorExpression, UnionAllExpression, CteJoinExpression)
        }
    }
}

Similar would be possible for other types of CTE

[shyamal890]

This is a much need feature in EF. Most of the enterprise applications need this and have to settle for SQL stored procedure which defeats the purpose of EF.

[roji]

Duplicate of #26486