ADO.NET SQL Server error category resolver for SQL Server and SQL Azure

ResolveErrorCategory.cs

        /// <summary>
        /// Examines exceptions for possible retry scenarios.
        /// </summary>
        public static DatabaseErrorCategory ResolveErrorCategory(SqlException ex)
        {
            bool isConnectionError = false;
            bool isDeadlockError = false;
            bool isTimeoutError = false;

            foreach (SqlError error in ex.Errors)
            {
                switch (error.Number)
                {
                    case 20: //The instance of SQL Server you attempted to connect to does not support encryption. (PMcE: amazingly, this is transient)
                    case 64: //A connection was successfully established with the server, but then an error occurred during the login process.
                    case 233: //The client was unable to establish a connection because of an error during connection initialization process before login
                    case 10053: //transport level error
                    case 10054: //transport level error
                    case 10060: //network or instance error
                    case 10061: //network or instance error
                    case 10928: //Azure out of resources
                    case 10929: //Azure out of resources
                    case 40143: //connection could not be initialized
                    case 40197: //the service encountered an error
                    case 40501: //service is busy
                    case 40613: //database unavailable
                        isConnectionError = true;
                        break;
                    case 3960: //snapshot isolation error
                    case 1205: //deadlock
                        isDeadlockError = true;
                        break;
                    case -2: //timeout
                        isTimeoutError = true;
                        break;
                    case 50000: //explicit TSQL RAISERROR
                        //see if this is a rethrow if a deadlock..
                        if (error.Message.Contains("Error 1205"))
                        {
                            isDeadlockError = true;
                        }
                        break;
                }
            }

            DatabaseErrorCategory category = DatabaseErrorCategory.Unknown;

            //the order we check these sets our priority of handling them.
            if (isDeadlockError)
                category = DatabaseErrorCategory.Deadlock;
            else if (isConnectionError)
                category = DatabaseErrorCategory.Connection;
            else if (isTimeoutError)
                category = DatabaseErrorCategory.Timeout;

            return category;
        }


    /// <summary>
    /// The type of error we experienced
    /// </summary>
    [Flags]
    public enum DatabaseErrorCategory
    {
        /// <summary>
        /// No recognized error type was determined
        /// </summary>
        Unknown = 0,

        /// <summary>
        /// The operation timed out
        /// </summary>
        Timeout = 1,

        /// <summary>
        /// The connection failed in some way
        /// </summary>
        Connection = 2,

        /// <summary>
        /// The operation failed due to DB deadlock
        /// </summary>
        Deadlock = 4,
    }