สอบถามเพิ่มเกี่ยวกับการใส่ SQL Server Function แปลง Password เป็น MD5 หน่อยคับ

SUBSTRING(sys.fn_sqlvarbasetostr(HASHBYTES('MD5', 'string')),3,32) 

strSQL = ("SELECT * FROM register WHERE username = '" + this.txtUsername.Text + "' AND [password] = SUBSTRING(sys.fn_sqlvarbasetostr(HASHBYTES('MD5', '"+this.txtPassword.Text+"')),3,32)  ");
           objCmd = new SqlCommand(strSQL, objConn);

strSQL = new StringBuilder();
            strSQL.Append("SELECT * FROM register");
            strSQL.Append("WHERE username = @sUsername");
            strSQL.Append("AND password = '" + EncMD5("@sPassword") +"'");
            objCmd = new SqlCommand(strSQL.ToString(), objConn);
            objCmd.Parameters.Add("@sUsername", SqlDbType.VarChar).Value = this.txtUsername.Text;
            objCmd.Parameters.Add("@sPassword", SqlDbType.VarChar).Value =  EncMD5("'"+ this.txtPassword.Text+ "'");

//** Password Md5 **//
        public string EncMD5(string input)
        {
            MD5 md5Hashfc = MD5.Create();
            byte[] data = md5Hashfc.ComputeHash(Encoding.Default.GetBytes(input));
            StringBuilder sBuilder = new StringBuilder();
            int i = 0;
            for (i = 0; i <= data.Length - 1; i++)
            {
                sBuilder.Append(data[i].ToString("x2"));

            }
            return sBuilder.ToString();
        }
        //**End Password Md5  **//