DeriveParameters

public static void DeriveParameters(DbCommand cmd, params object[] values)
        {
            AppRuntime.GuardArgument(cmd, "cmd");
            AppRuntime.GuardArgument(string.IsNullOrEmpty(cmd.CommandText), "cmd.CommandText");
            AppRuntime.GuardArgument(cmd.Connection == null, "cmd.Connection");
            AppRuntime.GuardArgument(values, "values");
            cmd.CommandType = CommandType.StoredProcedure;
            string key = "DeriveParameters_" + cmd.CommandText;
            DbParameter[] discoveredParameters = AppRuntime.Cache[key] as DbParameter[];
            if (discoveredParameters == null)
            {
                string qualifiedName = cmd.GetType().AssemblyQualifiedName;
                Type builderType = Type.GetType(qualifiedName.Insert(qualifiedName.IndexOf(','), "Builder"));
                MethodInfo method = builderType.GetMethod("DeriveParameters", BindingFlags.Public | BindingFlags.Static | BindingFlags.InvokeMethod);
                if (method == null)
                {
                    throw new ArgumentException("The specified provider factory doesn't support stored procedures.");
                }
                bool isClosed = cmd.Connection.State == ConnectionState.Closed;
                if (isClosed)
                {
                    cmd.Connection.Open();
                }
                method.Invoke(null, new object[] { cmd });
                if (isClosed)
                {
                    cmd.Connection.Close();
                }
                AppRuntime.Cache[key] = discoveredParameters = new DbParameter[cmd.Parameters.Count];
                for (int i = 0; i < discoveredParameters.Length; i++)
                {
                    (discoveredParameters[i] = cmd.Parameters[i]).Value = DBNull.Value;
                }
                cmd.Parameters.Clear();
            }
            //Always discoveredParameters[0].ParameterName == ReturnParameterName
            AppRuntime.GuardArgument(discoveredParameters.Length - 1 != values.Length, "The number of parameters doesn't match number of values for stored procedures.");
            if (!cmd.Parameters.Contains(ReturnParameterName))
            {
                cmd.Parameters.Add(((ICloneable)discoveredParameters[0]).Clone());
            }
            for (int i = 0; i < values.Length; i++)
            {
                DbParameter cloneParameter = discoveredParameters[i + 1];
                int index = cmd.Parameters.IndexOf(cloneParameter.ParameterName);
                if (index == -1)
                {
                    object cloned = ((ICloneable)cloneParameter).Clone();
                    if (!DbUtility.IsNullOrDBNull(values[i]))
                    {
                        ((DbParameter)cloned).Value = values[i];
                    }
                    cmd.Parameters.Add(cloned);
                }
                else
                {
                    cmd.Parameters[index].Value = values[i] ?? DBNull.Value;
                }
            }
        }