NpgsqlDataReader Select statement- Not Working for camelCase data Tables

Question

Hi I'm connecting to postgres database and transfer data to my local machine.

here is my code :

        public DataTable GetDataTable(string sql)
    {
        var conn = GetOpenConnection();
        var dt = new DataTable();

        var cmd = conn.CreateCommand();
        cmd.CommandText = sql;

        NpgsqlDataReader dr = null;

        try
        {
            dr = cmd.ExecuteReader();
            dt.Load(dr);
        }
        catch (Exception ex)
        {
            Log.Info(ex);
            throw;
        }
        finally
        {
            dr.Close();
            conn.Close();
        }

        return dt;
    }

Below scenarios working fine

sql = "SELECT * FROM test_db"

sql= "SELECT * FROM testdb"

But if; sql = "SELECT * FROM testDb" then I got exception

Error 42P01 "testdb" does not exist

I notice that several tables. If I used camelcase data tables name every time it throws an exception. Here is the code which I got my exception

dr = cmd.ExecuteReader();

So I would like to know can't I call camelCase tables? What is the best solution fro this ?

appreciate your feedback and answers !! Thank you