NLS_SORT and Oracle 11g vs 12c

dummy_data_script.txt

create table sortme(data varchar2(1));

insert into sortme(data) values('B');

insert into sortme(data) values('a');

insert into sortme(data) values('b');

insert into sortme(data) values('A');

results.txt

Query to be run is [SELECT data FROM (SELECT ROW_NUMBER() OVER (order by data ASC)
                                    peta_rn, sortme.* from sortme) peta_paged WHERE peta_rn>0 AND peta_rn<=100]


Connection string is [User Id=qa3; password=*******; data source=emtqa01_web]
Data before 'alter session'...
----------
A
B
a
b

Running [ALTER SESSION SET NLS_SORT=BINARY_AI]


Data after 'alter session'...
----------
A
B
a
b


Connection string is [User Id=qa3iad; password=*******; data source=emtiadq1_web]
Data before 'alter session'...
----------
A
B
a
b

Running [ALTER SESSION SET NLS_SORT=BINARY_AI]


Data after 'alter session'...
----------
a
A
B
b
Press any key to continue . . .

SortDiagnostic.cs

using System;
using System.Configuration;
using System.Text.RegularExpressions;
using Oracle.ManagedDataAccess.Client;

namespace SortDiagnostic
{
    class Program
    {
        const string queryToRun = @"SELECT data FROM (SELECT ROW_NUMBER() OVER (order by data ASC) 
                                    peta_rn, sortme.* from sortme) peta_paged WHERE peta_rn>0 AND peta_rn<=100";

        static void Main(string[] args)
        {
            Console.WriteLine("Query to be run is [{0}]", queryToRun);

            var connectionStrings = ConfigurationManager.AppSettings["connectionStringsToTry"].Split('|');
            foreach (var connStr in connectionStrings)
            {
                TryDatabase(connStr);
            }
        }

        static void TryDatabase(string connectionString)
        {
            Console.WriteLine();
            Console.WriteLine();
            Console.WriteLine("Connection string is [{0}]", Regex.Replace(connectionString, "password=[^;]+;", "password=*******;"));

            using (var conn = new OracleConnection { ConnectionString = connectionString })
            {
                conn.Open();

                using (var cmd = conn.CreateCommand())
                {
                    Console.WriteLine("Data before 'alter session'...");
                    Console.WriteLine("----------");
                    SpitOutData(cmd);

                    //try to get the sorting to be accent insensitive
                    const string alterSessionSql = "ALTER SESSION SET NLS_SORT=BINARY_AI";
                    cmd.CommandText = alterSessionSql;
                    cmd.ExecuteNonQuery();
                    Console.WriteLine();
                    Console.WriteLine("Running [{0}]", alterSessionSql);


                    Console.WriteLine();
                    Console.WriteLine();

                    Console.WriteLine("Data after 'alter session'...");
                    Console.WriteLine("----------");

                    SpitOutData(cmd);
                }
            }

        }

        static void SpitOutData(OracleCommand cmd)
        {
            cmd.CommandText = queryToRun;

            using (var reader = cmd.ExecuteReader())
            {
                while (reader.Read())
                {
                    Console.WriteLine(reader.GetString(0));
                }
            }

        }
    }
}