c#连接SQLite
SQLite这个精巧的小数据库，无需安装软件，只需要一个System.Data.SQLite.DLL文件即可操作SQLite数据库。SQLite是一个开源数据库，现在已变得越来越流行，它的体积很小，被广泛应用于各种不同类型的应用中。SQLite已经是世界上布署得最广泛的SQL数据库引擎，被用在无以计数的桌面电脑应用中，还有消费电子设备中，如移动电话、掌上电脑和MP3播放器等。SQLite的源码就放在公有领域（即WikiPedia的public domain)中。
本代码为网上收录的sqlite数据库操作类。
代码正文
Codeusing System;
using System.Collections.Generic;
using System.Text;
using System.Web;
using System.Configuration;
using System.Data;
using System.Data.SQLite;
namespace DAL
{
public class Sqlite
{
/// <summary>
/// 获得连接对象
/// </summary>
/// <returns></returns>
public static SQLiteConnection GetSQLiteConnection()
{
return new SQLiteConnection("Data Source=" + System.Web.HttpContext.Current.Server.MapPath(System.Configuration.ConfigurationManager.AppSettings["db"].ToString()));
}
private static void PrepareCommand(SQLiteCommand cmd, SQLiteConnection conn, string cmdText, params object[] p)
{
if (conn.State != ConnectionState.Open)
conn.Open();
cmd.Parameters.Clear();
cmd.Connection = conn;
cmd.CommandText = cmdText;
cmd.CommandType = CommandType.Text;
cmd.CommandTimeout = 30;
if (p != null)
{
foreach (object parm in p)
cmd.Parameters.AddWithValue(string.Empty, parm);
//for (int i = 0; i < p.Length; i++)
// cmd.Parameters[i].Value = p[i];
}
}
public static DataSet ExecuteDataset(string cmdText, params object[] p)
{
DataSet ds = new DataSet();
SQLiteCommand command = new SQLiteCommand();
using (SQLiteConnection connection = GetSQLiteConnection())
{
PrepareCommand(command, connection, cmdText, p);
SQLiteDataAdapter da = new SQLiteDataAdapter(command);
da.Fill(ds);
}
return ds;
}
public static DataRow ExecuteDataRow(string cmdText, params object[] p)
{
DataSet ds = ExecuteDataset(cmdText, p);
if (ds != null && ds.Tables.Count > 0 && ds.Tables[0].Rows.Count > 0)
return ds.Tables[0].Rows[0];
return null;
}
/// <summary>
/// 返回受影响的行数
/// </summary>
/// <param name="cmdText">a</param>
/// <param name="commandParameters">传入的参数</param>
/// <returns></returns>
public static int ExecuteNonQuery(string cmdText, params object[] p)
{
SQLiteCommand command = new SQLiteCommand();
using (SQLiteConnection connection = GetSQLiteConnection())
{
PrepareCommand(command, connection, cmdText, p);
return command.ExecuteNonQuery();
}
}
/// <summary>
/// 返回SqlDataReader对象
/// </summary>
/// <param name="cmdText"></param>
/// <param name="commandParameters">传入的参数</param>
/// <returns></returns>
public static SQLiteDataReader ExecuteReader(string cmdText, params object[] p)
{
SQLiteCommand command = new SQLiteCommand();
SQLiteConnection connection = GetSQLiteConnection();
try
{
PrepareCommand(command, connection, cmdText, p);
SQLiteDataReader reader = command.ExecuteReader(CommandBehavior.CloseConnection);
return reader;
}
catch
{
connection.Close();
throw;
}
}
/// <summary>
/// 返回结果集中的第一行第一列，忽略其他行或列
/// </summary>
/// <param name="cmdText"></param>
/// <param name="commandParameters">传入的参数</param>
/// <returns></returns>
public static object ExecuteScalar(string cmdText, params object[] p)
{
SQLiteCommand cmd = new SQLiteCommand();
using (SQLiteConnection connection = GetSQLiteConnection())
{
PrepareCommand(cmd, connection, cmdText, p);
return cmd.ExecuteScalar();
}
}
/// <summary>
/// 分页
/// </summary>
/// <param name="recordCount"></param>
/// <param name="pageIndex"></param>
/// <param name="pageSize"></param>
/// <param name="cmdText"></param>
/// <param name="countText"></param>
/// <param name="p"></param>
/// <returns></returns>
public static DataSet ExecutePager(ref int recordCount, int pageIndex, int pageSize, string cmdText, string countText, params object[] p)
{
if (recordCount < 0)
recordCount = int.Parse(ExecuteScalar(countText, p).ToString());
DataSet ds = new DataSet();
SQLiteCommand command = new SQLiteCommand();
using (SQLiteConnection connection = GetSQLiteConnection())
{
PrepareCommand(command, connection, cmdText, p);
SQLiteDataAdapter da = new SQLiteDataAdapter(command);
da.Fill(ds, (pageIndex - 1) * pageSize, pageSize, "result");
}
return ds;
}
}
}
System.Data.SQLite数据库通用类
针对对数据库的操作情况，分为以下几种情况：
创建数据库文件；
返回DataTable；
返回DataReader；
执行增删改，返回受影响的行数；
执行查询，返回第一行第一列（通常用于带有行函数的查询，如SUM/AVG/COUNT等）；
返回库中所有的表；
因为在System.Data.SQLite中不存在存储过程，所以所有的操作都是基于文本的SQL语句，为了避免SQL注入，所以使用了参数化的SQL语句，这个数据库通用类如下：
Codeusing System;
using System.Data;
using System.Data.Common;
using System.Data.SQLite; namespace SQLiteQueryBrowser
{
/// <summary>
/// 说明：这是一个针对System.Data.SQLite的数据库常规操作封装的通用类。
/// 作者：zhoufoxcn(周公）
/// 日期：2010-04-01
/// Blog:http://zhoufoxcn.blog.51cto.com or http://blog.csdn.net/zhoufoxcn
/// Version:0.1
/// </summary>
public class SQLiteDBHelper
{
private string connectionString = string.Empty;
/// <summary>
/// 构造函数
/// </summary>
/// <param name="dbPath">SQLite数据库文件路径</param>
public SQLiteDBHelper(string dbPath)
{
this.connectionString = "Data Source=" + dbPath;
}
/// <summary>
/// 创建SQLite数据库文件
/// </summary>
/// <param name="dbPath">要创建的SQLite数据库文件路径</param>
public static void CreateDB(string dbPath)
{
using (SQLiteConnection connection = new SQLiteConnection("Data Source=" + dbPath))
{
connection.Open();
using (SQLiteCommand command = new SQLiteCommand(connection))
{
command.CommandText = "CREATE TABLE Demo(id integer NOT NULL PRIMARY KEY AUTOINCREMENT UNIQUE)";
command.ExecuteNonQuery(); command.CommandText = "DROP TABLE Demo";
command.ExecuteNonQuery();
}
}
}
/// <summary>
/// 对SQLite数据库执行增删改操作，返回受影响的行数。
/// </summary>
/// <param name="sql">要执行的增删改的SQL语句</param>
/// <param name="parameters">执行增删改语句所需要的参数，参数必须以它们在SQL语句中的顺序为准</param>
/// <returns></returns>
public int ExecuteNonQuery(string sql, SQLiteParameter[] parameters)
{
int affectedRows = 0;
using (SQLiteConnection connection = new SQLiteConnection(connectionString))
{
connection.Open();
using (DbTransaction transaction = connection.BeginTransaction())
{
using (SQLiteCommand command = new SQLiteCommand(connection))
{
command.CommandText = sql;
if (parameters != null)
{
command.Parameters.AddRange(parameters);
}
affectedRows = command.ExecuteNonQuery();
}
transaction.Commit();
}
}
return affectedRows;
}
/// <summary>
/// 执行一个查询语句，返回一个关联的SQLiteDataReader实例
/// </summary>
/// <param name="sql">要执行的查询语句</param>
/// <param name="parameters">执行SQL查询语句所需要的参数，参数必须以它们在SQL语句中的顺序为准</param>
/// <returns></returns>
public SQLiteDataReader ExecuteReader(string sql, SQLiteParameter[] parameters)
{
SQLiteConnection connection = new SQLiteConnection(connectionString);
SQLiteCommand command = new SQLiteCommand(sql, connection);
if (parameters != null)
{
command.Parameters.AddRange(parameters);
}
connection.Open();
return command.ExecuteReader(CommandBehavior.CloseConnection);
}
/// <summary>
/// 执行一个查询语句，返回一个包含查询结果的DataTable
/// </summary>
/// <param name="sql">要执行的查询语句</param>
/// <param name="parameters">执行SQL查询语句所需要的参数，参数必须以它们在SQL语句中的顺序为准</param>
/// <returns></returns>
public DataTable ExecuteDataTable(string sql, SQLiteParameter[] parameters)
{
using (SQLiteConnection connection = new SQLiteConnection(connectionString))
{
using (SQLiteCommand command = new SQLiteCommand(sql, connection))
{
if (parameters != null)
{
command.Parameters.AddRange(parameters);
}
SQLiteDataAdapter adapter = new SQLiteDataAdapter(command);
DataTable data = new DataTable();
adapter.Fill(data);
return data;
}
} }
/// <summary>
/// 执行一个查询语句，返回查询结果的第一行第一列
/// </summary>
/// <param name="sql">要执行的查询语句</param>
/// <param name="parameters">执行SQL查询语句所需要的参数，参数必须以它们在SQL语句中的顺序为准</param>
/// <returns></returns>
public Object ExecuteScalar(string sql, SQLiteParameter[] parameters)
{
using (SQLiteConnection connection = new SQLiteConnection(connectionString))
{
using (SQLiteCommand command = new SQLiteCommand(sql, connection))
{
if (parameters != null)
{
command.Parameters.AddRange(parameters);
}
SQLiteDataAdapter adapter = new SQLiteDataAdapter(command);
DataTable data = new DataTable();
adapter.Fill(data);
return data;
}
}
}
/// <summary>
/// 查询数据库中的所有数据类型信息
/// </summary>
/// <returns></returns>
public DataTable GetSchema()
{
using (SQLiteConnection connection = new SQLiteConnection(connectionString))
{
connection.Open();
DataTable data=connection.GetSchema("TABLES");
connection.Close();
//foreach (DataColumn column in data.Columns)
//{
// Console.WriteLine(column.ColumnName);
//}
return data;
}
} }
}