Berkeley DB .net　进行添加和更新操作

使用hash格式的put方法，当key已经存在时，则更新该key的键值，若没有该key,则向数据库中插入一条新的记录，demo代码如下：

插入或是更新的代码片段：

Code

using System;

using System.Collections.Generic;

using System.IO;

using System.Linq;

using System.Runtime.Serialization.Formatters.Binary;

using System.Text;

using BerkeleyDb;

namespace BerkeleyDBDemo

{

public class Class18

{

static void Main(string[] args)

{

People a=new People()

{

Age=20,

Name="30"

};

Db db = new Db(DbCreateFlags.None);

try

{

DbFile dbf = db.Open(null, @"Tasks.asap", null, DbType.Hash, Db.OpenFlags.Create, 0);

MemoryStream stream = new MemoryStream();

BinaryFormatter formatter = new BinaryFormatter();

formatter.Serialize(stream, a);

DbEntry _key = DbEntry.InOut(Encoding.UTF8.GetBytes("1"));

DbEntry _data = DbEntry.InOut(stream.ToArray());

if (dbf.Put(null, ref _key, ref _data) != 0)

Console.Write("{0}:输入错误", "");

//dbf.Put(null, ref _key, ref _data);

dbf.Sync();//数据更新

}

catch (Exception ex)

{

Console.WriteLine("打开数据库Tasks.p失败");

}

db.Close();

}

}

}

遍历查看结果

using System;

using System.Collections.Generic;

using System.IO;

using System.Linq;

using System.Runtime.Serialization.Formatters.Binary;

using System.Text;

using BerkeleyDb;

namespace BerkeleyDBDemo

{

public class Class19

{

static void Main(string[] args)

{

//遍历数据

using (Db db = new Db(DbCreateFlags.None))

{

//这里如果应用Db.OpenFlags.Create则在启动后会覆盖同名文件，并新建同名文件

//Db.OpenFlags.Truncate会清空数据库

DbHash dbf = (DbHash)db.Open(null, @"Tasks.asap", null, DbType.Hash,

Db.OpenFlags.ThreadSafe, 0);

using (DbHashCursor cursor = dbf.OpenCursor(null, DbFileCursor.CreateFlags.None))

{

foreach (KeyDataPair kdp in cursor)

{

//int k = BitConverter.ToInt32(kdp.Key.Buffer, 0);

//Console.WriteLine("k={0}", k.ToString());

string k = Encoding.UTF8.GetString(kdp.Key.Buffer, 0, kdp.Key.Size);

Console.WriteLine("key={0}", k);

BinaryFormatter bf = new BinaryFormatter();

MemoryStream stream = new MemoryStream();

stream.Write(kdp.Data.Buffer, 0, kdp.Data.Size);

stream.Seek(0, SeekOrigin.Begin);

People p2 = (People)bf.Deserialize(stream);

Console.WriteLine("Age={0}", p2.Age);

Console.WriteLine("Name={0}", p2.Name);

}

}

}

Console.ReadLine();

}

}

}