# DbTable ʹÓÃ˵Ã÷ `NewLife.Data.DbTable` ÊÇÒ»¸öÇáÁ¿¼¶µÄ±í¸ñÊý¾ÝÈÝÆ÷£¬Ö§³Ö´ÓÊý¾Ý¿â¶ÁÈ¡¡¢¶þ½øÖÆ/Xml/Csv ÐòÁл¯¡¢Óë `DataTable` »¥×ª£¬ÒÔ¼°Ä£ÐͶÔÏóÓëÐÐÖ®¼äµÄÓ³Éä¡£ - ÃüÃû¿Õ¼ä£º`NewLife.Data` - Ö÷ÒªÀàÐÍ£º`DbTable`¡¢`DbRow` - µäÐͳ¡¾°£º - ´Ó `IDataReader`/`DbDataReader` ¶ÁÈ¡²éѯ½á¹û - Óë `DataTable` »¥×ª£¬Ìá¸ßÓë ADO.NET µÄ»¥²Ù×÷ - ½«±íÊý¾ÝÐòÁл¯Îª¶þ½øÖÆ¡¢XML¡¢CSV »òÊý¾Ý°ü - ½«Ä£ÐÍÁбíдÈëΪ±í£¬»ò½«±í¶ÁȡΪģÐÍÁбí ## ºËÐijÉÔ± - Áж¨Òå - `string[] Columns` ÁÐÃû¼¯ºÏ - `Type[] Types` ÁÐÀàÐͼ¯ºÏ - Êý¾Ý - `IList<object?[]> Rows` Ðм¯ºÏ - `int Total` ×ÜÐÐÊý - ¶ÁÈ¡ - `Read(IDataReader dr)` / `ReadAsync(DbDataReader dr)` - `ReadData(IDataReader dr, int[]? fields = null)`£º½ö¶ÁÈ¡Ö¸¶¨ÁУ¬`fields[i]` ±íʾԴÊý¾ÝÁÐË÷ÒýÓ³É䵽Ŀ±êÁÐ `i` - `Read(DataTable table)` ´Ó `DataTable` ¶ÁÈ¡ - ¶þ½øÖƶÁÈ¡£º`Read(Stream)`¡¢`ReadHeader(Binary)`¡¢`ReadData(Binary, rows)`¡¢`ReadRows(Binary, rows)` - Îļþ/Êý¾Ý°ü£º`LoadFile(path)`¡¢`LoadRows(path)`¡¢`Read(IPacket)`¡¢`Read(byte[])` - дÈë - `Write(Stream)`/`WriteHeader(Binary)`/`WriteData(Binary)`/`WriteData(Binary, int[] fields)` - `WriteRows(Binary, IEnumerable<object?[]>, int[]? fields = null)`/`WriteRow(...)` - `SaveFile(path)`/`SaveRows(path, rows, fields)` - `ToPacket()` תÊý¾Ý°ü - ת»» - `ToDataTable()`/`Write(DataTable)` - `ToJson(...)`/`WriteXml(Stream)`/`GetXml()`/`SaveCsv(path)`/`LoadCsv(path)` - Ä£ÐÍÓ³Éä - `WriteModels<T>(IEnumerable<T>)` ½«Ä£ÐÍдÈëΪ±í£¨½ö»ù´¡ÀàÐÍÊôÐÔ£© - `Cast<T>(IEnumerable<T>)` ½«Ä£ÐÍ°´ÁÐ˳ÐòתΪÐÐ - `ReadModels<T>()`/`ReadModels(Type)` ½«±íתΪģÐÍÁбí - ·ÃÎÊ - `Get<T>(rowIndex, name)`/`TryGet<T>(rowIndex, name, out value)` - `GetColumn(name)` ¸ù¾ÝÁÐÃûÕÒË÷Òý - ö¾Ù£º`foreach (var row in table)`£¬Ã¿¸ö `row` ÊÇ `DbRow` ## ¿ìËÙÉÏÊÖ ### 1) ´ÓÊý¾Ý¿â¶ÁÈ¡ ```csharp using var cmd = connection.CreateCommand(); cmd.CommandText = "select Id, Name, CreateTime from User"; using var reader = cmd.ExecuteReader(); var table = new DbTable(); table.Read(reader); Console.WriteLine(table.Total); // ÐÐÊý Console.WriteLine(table.Columns[0]); // ÁÐÃû ``` ½öÑ¡Ôñ²¿·ÖÁУº ```csharp // fields: ½«Ä¿±êÁÐ i Ó³Éäµ½Ô´ reader µÄÁÐË÷Òý fields[i] // ÀýÈçÖ»¶ÁµÚ 0 ºÍµÚ 2 ÁÐ int[] fields = [0, 2]; var table = new DbTable(); table.ReadHeader(reader); // ÏȶÁÈ¡Áж¨Òå table.ReadData(reader, fields); ``` ### 2) Óë DataTable »¥×ª ```csharp var dataTable = table.ToDataTable(); var table2 = new DbTable(); table2.Read(dataTable); ``` ### 3) ÐòÁл¯ - ¶þ½øÖÆ£º ```csharp using var fs = File.Create("users.db"); table.SaveFile("users.db"); // »ò table.Write(fs) var t2 = new DbTable(); t2.LoadFile("users.db"); ``` - XML/Csv£º ```csharp var xml = table.GetXml(); table.SaveCsv("users.csv"); ``` - Êý¾Ý°ü£º ```csharp var pk = table.ToPacket(); ``` ### 4) Ä£ÐÍÓ³Éä ```csharp public sealed class User { public Int32 Id { get; set; } public String Name { get; set; } = ""; public DateTime CreateTime { get; set; } } // Ä£ÐÍ -> ±í var users = new List<User> { new() { Id = 1, Name = "Stone", CreateTime = DateTime.UtcNow } }; var table = new DbTable(); table.WriteModels(users); // ±í -> Ä£ÐÍ var list = table.ReadModels<User>().ToList(); ``` ## ½ø½×˵Ã÷ - `fields` Ó³Éä¹æÔò - ¶ÁÈ¡£º`ReadData(dr, fields)` ½«Ä¿±êÁÐ `i` Ó³Éäµ½Ô´ÁÐË÷Òý `fields[i]`£¬¿ÕÖµ»á°´Ô´ÁÐÀàÐÍÌî³äĬÈÏÖµ£¨ÊýÖµ 0¡¢`false`¡¢`DateTime.MinValue` µÈ£©¡£ - дÈ룺`WriteData(bn, fields)`/`WriteRow(bn, row, fields)` ½«Ä¿±êÁÐ `i` дÈëÔ´ÐÐµÄ `row[fields[i]]`£»Èô `fields[i] == -1` Ôò°´Ä¿±êÁÐÀàÐÍдÈë¿ÕÖµ¡£ - Èç¹ûÒÔµü´úÆ÷·½Ê½Ïû·Ñ£º`ReadRows(bn, -1)` ¿É³ÖÐø¶ÁÈ¡ÖÁÁ÷ĩβ¡£ - `DbRow` Ìṩ¿ì½Ý·ÃÎÊ£º`row.Get<T>("Name")`¡£ ## ¼æÈÝÓë×¢Òâ - ¶þ½øÖƸñʽͷº¬»ÃÊýÓë°æ±¾£¬µ±Ç°°æ±¾ `3`£¬ÏòÇ°¼æÈݾɰ汾ʱ¼äдÈë¸ñʽ¡£ - MySQL ÌØÊâÈÕÆÚ£¨Èç `0000-00-00`£©¿ÉÄÜÔÚ¶ÁȡʱÒì³££¬ÄÚ²¿ÒÑÓà `try/catch` ºöÂÔ²¢Ìî³äĬÈÏÖµ¡£ - ¸ßÐÔÄÜ·¾¶±ÜÃâ´óÁ¿ LINQ/·´É䣻ÀàÐÍ¡¢ÁÐÃûµÈÒÑ»º´æÓÚ `DbTable` µÄ `Columns`/`Types`¡£ ## ±ä¸üÕªÒª£¨±¾´ÎÖع¹£© - ÐÞ¸´ `ReadData/ReadDataAsync` ÔÚ `fields` Ó³É䳡¾°ÏµÄÀàÐÍË÷Òý´íλÎÊÌâ¡£ - ÐÞ¸´ `WriteData(Binary, int[])` Óë `WriteRow(Binary, object?[], int[]?)` ÔÚ `idx < 0` ʱԽ½ç·ÃÎÊ `ts[idx]` µÄÎÊÌ⣬¸ÄΪ°´Ä¿±êÁÐÀàÐÍдÈë¿ÕÖµ¡£ - `Read(DataTable)` ÉèÖà `Total` ÓëÆäËû¶ÁÈ¡·½Ê½±£³ÖÒ»Ö¡£ - `GetXml()` ¸ÄΪͬ²½µÈ´ý `WriteXml` Íê³É£¬±ÜÃâ `Wait(15000)` ¿ÉÄܵ¼ÖÂÄÚÈݲ»ÍêÕû¡£ - ¸Ä½øö¾ÙÆ÷ʵÏÖ£¬Ö§³Ö `Reset()` ºóÖØÐÂö¾Ù¡£ ## ²Î¿¼ - Îĵµ£ºhttps://newlifex.com/core/dbtable - ÃüÃû¿Õ¼ä£º`NewLife.Data`