C# SQLiteDataReader.IsDBNull方法代码示例

        public string printToConsole(SQLiteDataReader readerDB, int index)
        {
            if (readerDB.IsDBNull(index))
            {
                //return "NULL";
                return "";
            }
            else
            {
                String dataObject = readerDB.GetFieldType(index).ToString();
                switch (dataObject)
                {
                    case "System.Int32":
                        return readerDB.GetInt32(index).ToString();
                    case "System.DateTime":
                        DateTime date = readerDB.GetDateTime(index);
                        return Convert.ToString(date);
                    case "System.String":
                        return readerDB.GetString(index);
                    default:
                        return "Unknown";
                }
            }

        }

 public static object ReadFloat(SQLiteDataReader reader, int idx)
 {
     try
     {
         if (reader.IsDBNull(idx))
             return 0;
         else
             return reader.GetFloat(idx);
     }
     catch (Exception)
     {
         return 0;
     }
 }

 protected void ReadDvbData(SQLiteDataReader r, IDictionary<string, int> field, DataRoot dataRoot, Dictionary<long, string> providers)
 {
     this.ShortName = DbSerializer.ReadUtf16(r, 16);
       this.RecordOrder = r.GetInt32(field["major"]);
       int serviceType = r.GetInt32(field["srvType"]);
       this.ServiceType = serviceType;
       this.SignalSource |= LookupData.Instance.IsRadioOrTv(serviceType);
       this.OriginalNetworkId = r.GetInt32(field["onid"]);
       this.TransportStreamId = r.GetInt32(field["tsid"]);
       this.ServiceId = r.GetInt32(field["progNum"]);
       this.VideoPid = r.GetInt32(field["vidPid"]);
       if (!r.IsDBNull(field["provId"]))
     this.Provider = providers.TryGet(r.GetInt64(field["provId"]));
 }

 public static object ReadBoolean(SQLiteDataReader reader, int idx)
 {
     try
     {
         if (reader.IsDBNull(idx))
             return false;
         else
             return reader.GetBoolean(idx);
     }
     catch (Exception)
     {
         return false;
     }
 }

        public static object ReadDateTime(SQLiteDataReader reader, int idx)
        {
            try
            {
                if (!reader.IsDBNull(idx))
                {
                    string val = reader.GetString(idx);
                    if(val.Length != 0)
                    {
                        return DateTime.Parse(val);
                    }
                }

                return new DateTime(1970, 1, 1);
            }
            catch (Exception)
            {
                return new DateTime(1970, 1, 1);
            }
        }

        private Entry ReadEntryAuthor(SQLiteDataReader reader)
        {
            Entry entry = new Entry();
            entry.ID = reader.GetInt32(0);
            if (!reader.IsDBNull(1))
            {
                entry.ParentID = reader.GetInt32(1);
            }
            else
            {
                entry.ParentID = null;
            }
            entry.AccountID = reader.GetInt32(2);
            entry.Title = reader.GetString(3);
            entry.Contents = reader.GetString(4);
            entry.Timestamp = reader.GetDateTime(5);

            entry.Author = new Account();
            entry.Author.ID = entry.AccountID;
            entry.Author.Name = reader.GetString(6);
            entry.Author.Email = reader.GetString(7);

            return entry;
        }

        private Entry ReadEntryAuthorVote(SQLiteDataReader reader)
        {
            Entry entry = new Entry();
            entry.ID = reader.GetInt32(0);
            if (!reader.IsDBNull(1))
            {
                entry.ID = reader.GetInt32(1);
            }
            else
            {
                entry.ParentID = null;
            }
            entry.AccountID = reader.GetInt32(2);
            entry.Title = reader.GetString(3);
            entry.Contents = reader.GetString(4);
            entry.Timestamp = reader.GetDateTime(5);

            entry.Author = new Account();
            entry.Author.ID = entry.AccountID;
            entry.Author.Name = reader.GetString(6);
            entry.Author.Email = reader.GetString(7);

            if (reader.IsDBNull(9))
            {
                entry.Vote = 0;
                entry.AuthorVote = false;
                entry.AuthorVoteUp = false;
                entry.AuthorVoteDown = false;
            }
            else
            {
                int vote = reader.GetInt32(9);
                entry.AuthorVote = true;
                if (vote > 0)
                {
                    entry.AuthorVoteUp = true;
                    entry.AuthorVoteDown = false;
                }
                else
                {
                    entry.AuthorVoteUp = false;
                    entry.AuthorVoteDown = true;
                }
            }

            return entry;
        }

 /// <summary>
 /// returns "" (empty string) if field is null
 /// </summary>
 /// <param name="rdr"></param>
 /// <param name="idx"></param>
 /// <returns></returns>
 private string GetNullableString(SQLiteDataReader rdr, int idx)
 {
     if (!rdr.IsDBNull(idx))
     {
         return rdr.GetString(idx);
     }
     else
     {
         return "";
     }
 }

        private Node ReadNode(SQLiteDataReader reader)
        {
            var node = new Node();

            node.Id = reader.GetInt64(0);
            node.Latitude = SQLiteSchemaTools.DBToGeo(reader.GetInt32(1));
            node.Longitude = SQLiteSchemaTools.DBToGeo(reader.GetInt32(2));

            // evaluate name
            if (!reader.IsDBNull(3))
            {
                var name = reader.GetString(3);
                EvaluateName(name, node);
            }

            return node;
        }

        private static Mount createMount(SQLiteDataReader reader)
        {
            if (!reader.Read()) {
                return null;
            }

            Mount mount = new Mount();
            mount.permanent = true;
            mount.id = reader.GetInt32(0);
            mount.title = reader.GetString(1);
            mount.name = reader.GetString(2);

            int tameitem = reader.IsDBNull(3) ? DATABASE_NULL : reader.GetInt32(3);
            if (tameitem > 0) mount.tameitemid = tameitem;
            else mount.tameitemid = -1;
            int tamecreature = reader.IsDBNull(4) ? DATABASE_NULL : reader.GetInt32(4);
            if (tamecreature > 0) mount.tamecreatureid = tamecreature;
            else mount.tamecreatureid = -1;
            mount.speed = reader.GetInt32(5);
            mount.tibiastore = reader.GetBoolean(6);
            mount.image = Image.FromStream(reader.GetStream(7));

            return mount;
        }

 public static List<WebExternalId> ExternalIdReader(SQLiteDataReader reader, int idx, object param)
 {
     ExternalSiteReaderParameters args = (ExternalSiteReaderParameters)param;
     List<WebExternalId> list = new List<WebExternalId>();
     if (!reader.IsDBNull(idx))
     {
         string val = (string)args.Reader.Invoke(reader, idx);
         if (!String.IsNullOrEmpty(val) && val != "0")
         {
             list.Add(new WebExternalId()
             {
                 Site = args.Site,
                 Id = val
             });
         }
     }
     return list;
 }

        private static Achievement createAchievement(SQLiteDataReader reader)
        {
            if (!reader.Read()) {
                return null;
            }

            Achievement achievement = new Achievement();
            achievement.id = reader.GetInt32(0);
            achievement.name = reader.GetString(1);
            achievement.grade = reader.IsDBNull(2) ? 1 : reader.GetInt32(2);
            achievement.points = reader.IsDBNull(3) ? 1 : reader.GetInt32(3);
            achievement.description = reader.IsDBNull(4) ? " " : reader.GetString(4);
            achievement.spoiler = reader.IsDBNull(5)  ? " " : reader.GetString(5);
            achievement.image = reader.IsDBNull(6) ? -1 : reader.GetInt32(6);
            achievement.imagetype = reader.IsDBNull(7) ? -1 : reader.GetInt32(7);

            return achievement;
        }

        private static HuntingPlace createHunt(SQLiteDataReader reader)
        {
            SQLiteCommand command;

            if (!reader.Read()) {
                return null;
            }

            HuntingPlace huntingPlace = new HuntingPlace();
            huntingPlace.permanent = true;
            huntingPlace.id = reader.GetInt32(0);
            huntingPlace.name = reader["name"].ToString();
            huntingPlace.level = reader.IsDBNull(2) ? DATABASE_NULL : reader.GetInt32(2);
            huntingPlace.exp_quality = reader.IsDBNull(3) ? DATABASE_NULL : reader.GetInt32(3);
            huntingPlace.loot_quality = reader.IsDBNull(4) ? DATABASE_NULL : reader.GetInt32(4);
            string imageName = reader.GetString(5).ToLower();
            Creature cr = getCreature(imageName);
            if (cr != null) {
                huntingPlace.image = cr.GetImage();
            } else {
                NPC npc = getNPC(imageName);
                if (npc != null) {
                    huntingPlace.image = npc.GetImage();
                } else {
                    throw new Exception("Unrecognized npc or creature image.");
                }
            }
            huntingPlace.city = reader["city"].ToString();

            // Hunting place coordinates
            command = new SQLiteCommand(String.Format("SELECT x, y, z FROM HuntingPlaceCoordinates WHERE huntingplaceid={0}", huntingPlace.id), mainForm.conn);
            reader = command.ExecuteReader();
            while (reader.Read()) {
                Coordinate c = new Coordinate();
                c.x = reader.IsDBNull(0) ? DATABASE_NULL : reader.GetInt32(0);
                c.y = reader.IsDBNull(1) ? DATABASE_NULL : reader.GetInt32(1);
                c.z = reader.IsDBNull(2) ? DATABASE_NULL : reader.GetInt32(2);
                huntingPlace.coordinates.Add(c);
            }
            // Hunting place directions
            command = new SQLiteCommand(String.Format("SELECT beginx, beginy, beginz,endx, endy, endz, ordering, description, settings FROM HuntDirections WHERE huntingplaceid={0} ORDER BY ordering", huntingPlace.id), mainForm.conn);
            reader = command.ExecuteReader();
            while (reader.Read()) {
                Directions d = new Directions();
                d.huntingplaceid = huntingPlace.id;
                d.begin = new Coordinate(reader.GetInt32(0), reader.GetInt32(1), reader.GetInt32(2));
                d.end = new Coordinate(reader.GetInt32(3), reader.GetInt32(4), reader.GetInt32(5));
                d.ordering = reader.GetInt32(6);
                d.description = reader["description"].ToString();
                d.settings = reader.GetString(8);
                huntingPlace.directions.Add(d);
            }

            // Hunting place creatures
            command = new SQLiteCommand(String.Format("SELECT creatureid FROM HuntingPlaceCreatures WHERE huntingplaceid={0}", huntingPlace.id), mainForm.conn);
            reader = command.ExecuteReader();
            while (reader.Read()) {
                int creatureid = reader.GetInt32(0);
                huntingPlace.creatures.Add(creatureid);
            }
            // Hunting place requirements
            command = new SQLiteCommand(String.Format("SELECT questid, requirementtext FROM HuntRequirements WHERE huntingplaceid={0}", huntingPlace.id), mainForm.conn);
            reader = command.ExecuteReader();
            while (reader.Read()) {
                Requirements r = new Requirements();
                r.huntingplaceid = huntingPlace.id;
                int questid = reader.IsDBNull(0) ? DATABASE_NULL : reader.GetInt32(0);
                r.quest = questIdMap[questid];
                r.notes = reader["requirementtext"].ToString();
                huntingPlace.requirements.Add(r);
            }
            return huntingPlace;
        }

 internal static string ReadUtf16(SQLiteDataReader r, int fieldIndex)
 {
   if (r.IsDBNull(fieldIndex))
     return null;
   byte[] nameBytes = new byte[200];
   int nameLen = (int)r.GetBytes(fieldIndex, 0, nameBytes, 0, nameBytes.Length);
   return Encoding.BigEndianUnicode.GetString(nameBytes, 0, nameLen);
 }

//.........这里部分代码省略.........
                    e.LineCssClass = strLineCssClass;
                    report.OutputLine(this, e);
                    if (e.Output == false)
                        continue;

                    strLineCssClass = e.LineCssClass;
                }
#endif

                // strResult.Append("<tr class='" + strLineCssClass + "'>\r\n");
                writer.WriteStartElement("tr");
                writer.WriteAttributeString("class", strLineCssClass);

                // 列循环
                for (j = 0; j < report.Count; j++)
                {
                    PrintColumn column = (PrintColumn)report[j];

                    if (column.ColumnNumber < -1)
                    {
                        throw (new Exception("PrintColumn对象ColumnNumber列尚未初始化，位置" + Convert.ToString(j)));
                    }

                    string strText = "";
                    if (column.ColumnNumber != -1)
                    {
                        if (string.IsNullOrEmpty(column.Eval) == false)
                        {
                            // engine.SetGlobalValue("cell", line.GetObject(column.ColumnNumber));
                            strText = engine.Evaluate(column.Eval).ToString();
                        }
                        else if (column.DataType == DataType.PriceDouble)
                        {
                            if (table.IsDBNull(column.ColumnNumber /**/) == true)
                                strText = column.DefaultValue;
                            else
                            {
                                double v = table.GetDouble(column.ColumnNumber);
                                /*
                                NumberFormatInfo provider = new NumberFormatInfo();
                                provider.NumberDecimalDigits = 2;
                                provider.NumberGroupSeparator = ".";
                                provider.NumberGroupSizes = new int[] { 3 };
                                strText = Convert.ToString(v, provider);
                                 * */
                                strText = v.ToString("N", nfi);
                            }
                        }
                        else if (column.DataType == DataType.PriceDecimal)
                        {
                            if (table.IsDBNull(column.ColumnNumber) == true)
                                strText = column.DefaultValue;
                            else
                            {
                                decimal v = table.GetDecimal(column.ColumnNumber);
                                strText = v.ToString("N", nfi);
                            }
                        }
                        else if (column.DataType == DataType.PriceDecimal)
                        {
                            if (table.IsDBNull(column.ColumnNumber) == true)
                                strText = column.DefaultValue;
                            else
                            {
                                decimal v = table.GetDecimal(column.ColumnNumber);
                                strText = v.ToString("N", nfi);