ForeverLearnNeverMaster questions

• Why do these three pieces of LINQ code produce different (or erroneous) results?
• Where should I perform a check to see if a value already exists in the database when performing validation in MVVM using IDataErrorInfo?
• In a layered architecture using Entity Framework, should I return POCO classes from the BLL? (Architecture guidance needed)
• In the List<T>.Sort() method, is an item ever compared to itself?
• Is it okay to set instance variables in a Django class based view?

ForeverLearnNeverMaster answers