Sqlite 操作类代码

　　ADO.NET 提供程序是香港(貌似)一个公司提供的.项目地址见:http://sourceforge.net/projects/sqlite-dotnet2

　　2. 对SQLite.NET的封装,提供一个简单的操作帮助类.

SQLiteHelper

复制代码 代码如下:

/**//**

* SQLite操作的帮助类.

*

* Author: egmkang.wang

* Date: 2009-06-21

*/

namespace System.Data.SQLite

{

using System.Data;

using System.Data.SQLite;

using System.IO;

public class SqliteHelper

{

private static string pwd = "PWD";

private static string path = Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().GetName().CodeBase) + "\\sqliteTest.db";

private static string connString = string.Format("Data Source =\"{0}\"", path, pwd);

/**//// <summary>

/// 返回数据库链接字符串

/// </summary>

public static string ConnString

{

get { return connString; }

}

/**//// <summary>

/// 执行SQL语句,返回受影响的行数

/// </summary>

/// <param name="cmdText">需要被执行的SQL语句</param>

/// <returns>受影响的行数</returns>

public static int ExecuteNonQuery(string cmdText)

{

return ExecuteNonQuery(ConnString, cmdText);

}

/**//// <summary>

/// 执行带有事务的SQL语句

/// </summary>

/// <param name="trans">事务</param>

/// <param name="cmdText">SQL语句</param>

/// <returns>受影响的行数</returns>

public static int ExecuteNonQuery(SQLiteTransaction trans, string cmdText, params SQLiteParameter[] parameters)

{

int val = 0;

using (SQLiteCommand cmd = new SQLiteCommand())

{

PrepareCommand(cmd, (SQLiteConnection)trans.Connection, trans, cmdText, parameters);

val = cmd.ExecuteNonQuery();

cmd.Parameters.Clear();

}

return val;

}

/**//// <summary>

/// 执行SQL语句,返回受影响的行数

/// </summary>

/// <param name="connString">连接字符串</param>

/// <param name="cmdText">SQL语句</param>

/// <param name="parameters">SQL的参数</param>

/// <returns>受影响的行数</returns>

public static int ExecuteNonQuery(string connString, string cmdText, params SQLiteParameter[] parameters)

{

using (SQLiteConnection conn = new SQLiteConnection(connString))

{

return ExecuteNonQuery(conn, cmdText, parameters);

}

}

/**//// <summary>

/// 执行SQL语句,返回受影响的行数

/// </summary>

/// <param name="connection">数据库链接</param>

/// <param name="cmdText">SQL语句</param>

/// <param name="parameters">参数</param>

/// <returns>受影响的行数</returns>

public static int ExecuteNonQuery(SQLiteConnection connection, string cmdText, params SQLiteParameter[] parameters)

{

int val = 0;

using (SQLiteCommand cmd = new SQLiteCommand())

{

PrepareCommand(cmd, connection, null, cmdText, parameters);

val = cmd.ExecuteNonQuery();

cmd.Parameters.Clear();

}

return val;

}

/**//// <summary>

/// 执行查询,并返回结果集的第一行的第一列.其他所有的行和列被忽略.

/// </summary>

/// <param name="cmdText">SQL 语句</param>

/// <returns>第一行的第一列的值</returns>

public static object ExecuteScalar(string cmdText)

{

return ExecuteScalar(ConnString, cmdText);

}

/**//// <summary>

/// 执行查询,并返回结果集的第一行的第一列.wjeoXpgLG其他所有的行和列被忽略.

/// </summary>

/// <param name="connString">连接字符串</param>

/// <param name="cmdText">SQL 语句</param>

/// <returns>第一行的第一列的值</returns>

public static object ExecuteScalar(string connString, string cmdText)

{

using (SQLiteConnection conn = new SQLiteConnection(connString))

{

return ExecuteScalar(conn, cmdText);

}

}

/**//// <summary>

/// 执行查询,并返回结果集的第一行的第一列.其他所有的行和列被忽略.

/// </summary>

/// <param name="connection">数据库链接</param>

/// <param name="cmdText">SQL 语句</param>

/// <returns>第一行的第一列的值</returns>

public static object ExecuteScalar(SQLiteConnection connection, string cmdText)

{

object val;

using (SQLiteCommand cmd = new SQLiteCommand())

{

PrepareCommand(cmd, connection, null, cmdText);

val = cmd.ExecuteScalar();

}

return val;

}

/**//// <summary>

/// 执行SQL语句,返回结果集的DataReader

/// </summaryhttp://www.devze.com>

/// <param name="cmdText">SQL语句</param>

/// <param name="parameters">参数</param>

/// <returns>结果集的DataReader</returns>

public static SQLiteDataReader ExecuteReader(string cmdText, params SQLiteParameter[] parameters)

{

return ExecuteReader(ConnString, cmdText, parameters);

}

/**//// <summary>

/// 执行SQL语句,返回结果集的DataReader

/// </summary>

/// <param name="connString">连接字符串</param>

/// <param name="cmdText">SQL语句</param>

/// <param name="parameters">参数</param>

/// <returns>结果集的DataReader</returns>

public static SQLiteDataReader ExecuteReader(strin编程客栈g connString, string cmdText, params SQLiteParameter[] parameters)

{

SQLiteConnection conn = new SQLiteConnection(connString);

SQLiteCommand cmd = new SQLiteCommand();

try

{

PrepareCommand(cmd, conn, null, cmdText, parameters);

SQLiteDataReader rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);

cmd.Parameters.Clear();

return rdr;

}

catch

{

conn.Close();

throw;

}

}

/**//// <summary>

/// 预处理Command对象,数据库链接,事务,需要执行的对象,参数等的初始化

/// </summary>

/// <param name="cmd">Command对象</param>

/// <param name="conn">Connection对象</param>

/// <param name="trans">Transcation对象</param>

/// <param name="cmdText">SQL Text</param>

/// <param name="parameters">参数实例</param>

private static void PrepareCommand(SQLiteCommand cmd, SQLiteConnection conn, SQLiteTransaction trans, string cmdText, params SQLiteParameter[] parameters)

{

if (conn.State != ConnectionState.Open)

conn.Open();

cmd.Connection = conn;

cmd.CommandText = cmdText;

if (trans != null)

cmd.Transaction = trans;

if (null != parameters && parameters.Length > 0)

{

cmd.Parameters.AddRange(parameters);

}

}

}

}

　　3. 增删改查:

复制代码 代码如下:

Insert,Delete,Update

const string s_AddressTreeIntoSQLite = "Insert into [AddressTree] ([Id],[ItemType],[ParentId],[Name]) values (@Id,@ItemType,@ParentId,@Name);";

SqliteHelper.ExecuteNonQuery(tran, s_AddressTreeIntoSQLite,

//new SQLi编程客栈teParameter[] here

);

Select

const string s_AddresTreeFromSqlCE = "Select [Id],[ItemType],[ParentId],[Name] From [AddressTree];";

using (SqlCeDataReader rdr = SqlCeHelper.ExecuteReader(s_AddresTreeFromSqlCE ))

{

while (rdr.Read())

{

//Readhttp://www.devze.com Data Here

}

}

　　4. 其他

　　SQLite性能绝对强悍.四表连接查询,查询200次,SQL CE需要44秒(with index),SQLite只需要3-6秒(with index).

插入,删除更新性能参见http://www.cnblogs.com/egmkang/archive/2009/06/06/1497678.html

　　PS:最近发现执行sql的时候,最好使用单一的长连接,而不是ConnectionString.原因很简单,嵌入式数据库没有连接池技术,

在进行数据库查询中的链接的打开关闭费用相对来说比较高昂.这一点在写程序的时候注意以下.

　　还有,有关二进制资源,需要及时释放,例如SqlCommand,这些在写Web 程开发者_数据库教程序的时候体验不是很大,毕竟那种环境拥有大量

的内存,GC的效率又是比较高.