SQLite DBHelp

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;
            }
        }

    }
}