CASE WHEN ((CASE WHEN ([Extent1].[Discriminator] = N'Person') THEN cast(1 as bit) ELSE cast(0 as bit) END) = 1) THEN CAST(NULL AS varchar(1)) WHEN (([Project6].[C1] = 1) AND ([Project6].[C1] IS NOT NULL) AND ( NOT (([Project6].[C2] = 1) AND ([Project6].[C2] IS NOT NULL))) AND ( NOT (([Project6].[C3] = 1) AND ([Project6].[C3] IS NOT NULL))) AND ( NOT (([Project6].[C4] = 1) AND ([Project6].[C4] IS NOT NULL)))) THEN [Project6].[Name] WHEN (([Project6].[C2] = 1) AND ([Project6].[C2] IS NOT NULL)) THEN [Project6].[Name] WHEN (([Project1].[C1] = 1) AND ([Project1].[C1] IS NOT NULL)) THEN CAST(NULL AS varchar(1)) WHEN (([Project6].[C4] = 1) AND ([Project6].[C4] IS NOT NULL)) THEN [Project6].[Name] WHEN (([Project2].[C1] = 1) AND ([Project2].[C1] IS NOT NULL)) THEN CAST(NULL AS varchar(1)) WHEN (([Project6].[C3] = 1) AND ([Project6].[C3] IS NOT NULL)) THEN [Project6].[Name] END AS [C2], 
CASE WHEN ((CASE WHEN ([Extent1].[Discriminator] = N'Person') THEN cast(1 as bit) ELSE cast(0 as bit) END) = 1) THEN CAST(NULL AS varchar(1)) WHEN (([Project6].[C1] = 1) AND ([Project6].[C1] IS NOT NULL) AND ( NOT (([Project6].[C2] = 1) AND ([Project6].[C2] IS NOT NULL))) AND ( NOT (([Project6].[C3] = 1) AND ([Project6].[C3] IS NOT NULL))) AND ( NOT (([Project6].[C4] = 1) AND ([Project6].[C4] IS NOT NULL)))) THEN [Project6].[Family] WHEN (([Project6].[C2] = 1) AND ([Project6].[C2] IS NOT NULL)) THEN [Project6].[Family] WHEN (([Project1].[C1] = 1) AND ([Project1].[C1] IS NOT NULL)) THEN CAST(NULL AS varchar(1)) WHEN (([Project6].[C4] = 1) AND ([Project6].[C4] IS NOT NULL)) THEN [Project6].[Family] WHEN (([Project2].[C1] = 1) AND ([Project2].[C1] IS NOT NULL)) THEN CAST(NULL AS varchar(1)) WHEN (([Project6].[C3] = 1) AND ([Project6].[C3] IS NOT NULL)) THEN [Project6].[Family] END AS [C3], 
CASE WHEN ((CASE WHEN ([Extent1].[Discriminator] = N'Person') THEN cast(1 as bit) ELSE cast(0 as bit) END) = 1) THEN CAST(NULL AS datetime2) WHEN (([Project6].[C1] = 1) AND ([Project6].[C1] IS NOT NULL) AND ( NOT (([Project6].[C2] = 1) AND ([Project6].[C2] IS NOT NULL))) AND ( NOT (([Project6].[C3] = 1) AND ([Project6].[C3] IS NOT NULL))) AND ( NOT (([Project6].[C4] = 1) AND ([Project6].[C4] IS NOT NULL)))) THEN [Project6].[DateOfBirth] WHEN (([Project6].[C2] = 1) AND ([Project6].[C2] IS NOT NULL)) THEN [Project6].[DateOfBirth] WHEN (([Project1].[C1] = 1) AND ([Project1].[C1] IS NOT NULL)) THEN CAST(NULL AS datetime2) WHEN (([Project6].[C4] = 1) AND ([Project6].[C4] IS NOT NULL)) THEN [Project6].[DateOfBirth] WHEN (([Project2].[C1] = 1) AND ([Project2].[C1] IS NOT NULL)) THEN CAST(NULL AS datetime2) WHEN (([Project6].[C3] = 1) AND ([Project6].[C3] IS NOT NULL)) THEN [Project6].[DateOfBirth] END AS [C4],

PM> Update-Database
Specify the '-Verbose' flag to view the SQL statements being applied to the target database.
Applying explicit migrations: [201510160239047_Initial, 201510182128076_AddCodeToArticle, 201510221124200_AddedScoreProperty, 201512220940192_RemoveUniqueOfTeacherTable, 201512221245065_RemoveConstraint, 201512221428430_removeNotification].
Applying explicit migration: 201510160239047_Initial.
Configuration option 'filestream access level' changed from 2 to 2. Run the RECONFIGURE statement to install.
System.Data.SqlClient.SqlException (0x80131904): FILESTREAM feature is disabled.
   at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
   at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
   at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)
   at System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady)
   at System.Data.SqlClient.SqlCommand.RunExecuteNonQueryTds(String methodName, Boolean async, Int32 timeout, Boolean asyncWrite)
   at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource`1 completion, String methodName, Boolean sendToPipe, Int32 timeout, Boolean asyncWrite)
   at System.Data.SqlClient.SqlCommand.ExecuteNonQuery()
   at System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.<NonQuery>b__0(DbCommand t, DbCommandInterceptionContext`1 c)
   at System.Data.Entity.Infrastructure.Interception.InternalDispatcher`1.Dispatch[TTarget,TInterceptionContext,TResult](TTarget target, Func`3 operation, TInterceptionContext interceptionContext, Action`3 executing, Action`3 executed)
   at System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.NonQuery(DbCommand command, DbCommandInterceptionContext interceptionContext)
   at System.Data.Entity.Internal.InterceptableDbCommand.ExecuteNonQuery()
   at System.Data.Entity.Migrations.DbMigrator.ExecuteSql(MigrationStatement migrationStatement, DbConnection connection, DbTransaction transaction, DbInterceptionContext interceptionContext)
   at System.Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.ExecuteSql(MigrationStatement migrationStatement, DbConnection connection, DbTransaction transaction, DbInterceptionContext interceptionContext)
   at System.Data.Entity.Migrations.DbMigrator.ExecuteStatementsInternal(IEnumerable`1 migrationStatements, DbConnection connection, DbInterceptionContext interceptionContext)
   at System.Data.Entity.Migrations.DbMigrator.ExecuteStatementsInternal(IEnumerable`1 migrationStatements, DbConnection connection)
   at System.Data.Entity.Migrations.DbMigrator.<>c__DisplayClass30.<ExecuteStatements>b__2e()
   at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.<>c__DisplayClass1.<Execute>b__0()
   at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute[TResult](Func`1 operation)
   at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute(Action operation)
   at System.Data.Entity.Migrations.DbMigrator.ExecuteStatements(IEnumerable`1 migrationStatements, DbTransaction existingTransaction)
   at System.Data.Entity.Migrations.DbMigrator.ExecuteStatements(IEnumerable`1 migrationStatements)
   at System.Data.Entity.Migrations.Infrastructure.MigratorBase.ExecuteStatements(IEnumerable`1 migrationStatements)
   at System.Data.Entity.Migrations.DbMigrator.ExecuteOperations(String migrationId, VersionedModel targetModel, IEnumerable`1 operations, IEnumerable`1 systemOperations, Boolean downgrading, Boolean auto)
   at System.Data.Entity.Migrations.DbMigrator.ApplyMigration(DbMigration migration, DbMigration lastMigration)
   at System.Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.ApplyMigration(DbMigration migration, DbMigration lastMigration)
   at System.Data.Entity.Migrations.DbMigrator.Upgrade(IEnumerable`1 pendingMigrations, String targetMigrationId, String lastMigrationId)
   at System.Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.Upgrade(IEnumerable`1 pendingMigrations, String targetMigrationId, String lastMigrationId)
   at System.Data.Entity.Migrations.DbMigrator.UpdateInternal(String targetMigration)
   at System.Data.Entity.Migrations.DbMigrator.<>c__DisplayClassc.<Update>b__b()
   at System.Data.Entity.Migrations.DbMigrator.EnsureDatabaseExists(Action mustSucceedToKeepDatabase)
   at System.Data.Entity.Migrations.Infrastructure.MigratorBase.EnsureDatabaseExists(Action mustSucceedToKeepDatabase)
   at System.Data.Entity.Migrations.DbMigrator.Update(String targetMigration)
   at System.Data.Entity.Migrations.Infrastructure.MigratorBase.Update(String targetMigration)
   at System.Data.Entity.Migrations.Design.ToolingFacade.UpdateRunner.Run()
   at System.AppDomain.DoCallBack(CrossAppDomainDelegate callBackDelegate)
   at System.AppDomain.DoCallBack(CrossAppDomainDelegate callBackDelegate)
   at System.Data.Entity.Migrations.Design.ToolingFacade.Run(BaseRunner runner)
   at System.Data.Entity.Migrations.Design.ToolingFacade.Update(String targetMigration, Boolean force)
   at System.Data.Entity.Migrations.UpdateDatabaseCommand.<>c__DisplayClass2.<.ctor>b__0()
   at System.Data.Entity.Migrations.MigrationsDomainCommand.Execute(Action command)
ClientConnectionId:ada71343-c349-41c6-8ac0-e9f983f57e85
Error Number:5591,State:3,Class:16
FILESTREAM feature is disabled.

if
   if
     if
       if
         do something
       endif
     endif
   endif
 endif

namespace Refactoring.Day9.RemoveArrowhead.Before
{
    public class Role
    {
        public string RoleName { set; get; }
        public string UserName { set; get; }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;

namespace Refactoring.Day9.RemoveArrowhead.Before
{
    public class RoleRepository
    {
        private IList<Role> _rolesList = new List<Role>();

        public IEnumerable<Role> Roles { get { return _rolesList; } }

        public void AddRole(string username, string roleName)
        {
            if (!string.IsNullOrWhiteSpace(roleName))
            {
                if (!string.IsNullOrWhiteSpace(username))
                {
                    if (!IsInRole(username, roleName))
                    {
                        _rolesList.Add(new Role 
                        {
                            UserName=username, 
                            RoleName=roleName
                        }); 
                    }
                    else
                    {
                        throw new InvalidOperationException("User is already in this role.");
                    }
                }
                else
                {
                    throw new ArgumentNullException("username");
                }
            }
            else
            {
                throw new ArgumentNullException("roleName");
            }
        }

        public bool IsInRole(string username, string roleName)
        {
            return _rolesList.Any(x => x.RoleName == roleName && x.UserName == username);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;

namespace Refactoring.Day9.RemoveArrowhead.After
{
    public class RoleRepository
    {
        private IList<Role> _rolesList = new List<Role>();

        public IEnumerable<Role> Roles { get { return _rolesList; } }

        public void AddRole(string username, string roleName)
        {
            if (string.IsNullOrWhiteSpace(roleName))
                throw new ArgumentNullException("roleName");

            if (string.IsNullOrWhiteSpace(username))
                throw new ArgumentNullException("username");

            if (IsInRole(username, roleName))
                throw new InvalidOperationException("User is already in this role.");

            _rolesList.Add(new Role
            {
                UserName = username,
                RoleName = roleName
            });
        }

        public bool IsInRole(string username, string roleName)
        {
            return _rolesList.Any(x => x.RoleName == roleName && x.UserName == username);
        }
    }
}