SQLite介绍和使用

SQLite特点：

（1）轻量级，跨平台的关系型数据库，所以支持视图，事务，触发器等。

（2）零配置-无需安装和管理配置，存储在单一磁盘文件中的完整的数据库

（3）数据库文件可共享，支持多种开发语言。

 

SQLite应用场景：

适用于并发量低，访问需求高于写入操作的一些引用

例如，最近的项目里，在客户的文件服务器下，需要要建立文件路径的索引，并能够文件打包下载，考虑到不想装单独的数据库，于是乎便用了SQLite

 

SQLite使用：

封装SQliteHelper类。

 public static class SqliteHelper
    {
        private static string connectionString =  ConfigurationManager.ConnectionStrings["SqliteConnectionstring"].ConnectionString;
         
        /// <summary>
        /// 创建一个数据库文件。如果存在同名数据库文件，则会覆盖。
        /// </summary>
        /// <param name="dbName">数据库文件名。为null或空串时不创建。</param>
        /// <param name="password">（可选）数据库密码，默认为空。</param>
        /// <exception cref="Exception"></exception>
        public static void CreateDB(string dbName)
        {
            SQLiteConnection conn = null;
            string dbPath = "Data Source ="+ connectionString+"/"+dbName + ".db";
            conn = new SQLiteConnection(dbPath);//创建数据库实例，指定文件位置  
            conn.Open();//打开数据库，若文件不存在会自动创建  
            string sql = "CREATE TABLE IF NOT EXISTS T_BuildChildPath(Id integer  IDENTITY(1,1), ProductsCode nvarchar(100), CodePath nvarchar(100), CreateTime  datetime);";//建表语句  
            SQLiteCommand cmdCreateTable = new SQLiteCommand(sql, conn);
            cmdCreateTable.ExecuteNonQuery();//如果表不存在，创建数据表  
            conn.Close();
        }
        /// <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>
        /// <exception cref="Exception"></exception>
        public static int ExecuteNonQuery(string sql, params SQLiteParameter[] parameters)
        {
            int affectedRows = 0;
            using (SQLiteConnection connection = new SQLiteConnection(connectionString))
            {
                using (SQLiteCommand command = new SQLiteCommand(connection))
                {
                    try
                    {
                        connection.Open();
                        command.CommandText = sql;
                        
                        if (parameters.Length != 0)
                        {
                            command.Parameters.AddRange(parameters);
                        }
                        affectedRows = command.ExecuteNonQuery();
                    }
                    catch (Exception ex) { throw; }
                }
            }
            return affectedRows;
        }
        public static int ExecuteNonQuery(string sql )
        {
            int affectedRows = 0;
            using (SQLiteConnection connection = new SQLiteConnection(connectionString))
            {
                using (SQLiteCommand command = new SQLiteCommand(connection))
                {
                    try
                    {
                        connection.Open();
                        command.CommandText = sql;
                       
                        affectedRows = command.ExecuteNonQuery();
                    }
                    catch (Exception ex) { throw; }
                }
            }
            return affectedRows;
        }
        /// <summary>
        /// 批量处理数据操作语句。
        /// </summary>
        /// <param name="list">SQL语句集合。</param>
        /// <exception cref="Exception"></exception>
        public static  void ExecuteNonQueryBatch(List<KeyValuePair<string,  SQLiteParameter[]>> list)
        {
            using (SQLiteConnection conn = new SQLiteConnection(connectionString))
            {
                try { conn.Open(); }
                catch { throw; }
                using (SQLiteTransaction tran = conn.BeginTransaction())
                {
                    using (SQLiteCommand cmd = new SQLiteCommand(conn))
                    {
                        try
                        {
                            foreach (var item in list)
                            {
                                cmd.CommandText = item.Key;
                                if (item.Value != null)
                                {
                                    cmd.Parameters.AddRange(item.Value);
                                }
                                cmd.ExecuteNonQuery();
                            }
                            tran.Commit();
                        }
                        catch (Exception) { tran.Rollback(); throw; }
                    }
                }
            }
        }
        /// <summary>
        /// 执行查询语句，并返回第一个结果。
        /// </summary>
        /// <param name="sql">查询语句。</param>
        /// <returns>查询结果。</returns>
        /// <exception cref="Exception"></exception>
        public static object ExecuteScalar(string sql, params SQLiteParameter[]  parameters)
        {
            using (SQLiteConnection conn = new SQLiteConnection(connectionString))
            {
                using (SQLiteCommand cmd = new SQLiteCommand(conn))
                {
                    try
                    {
                        conn.Open();
                        cmd.CommandText = sql;
                        if (parameters.Length != 0)
                        {
                            cmd.Parameters.AddRange(parameters);
                        }
                        return cmd.ExecuteScalar();
                    }
                    catch (Exception) { throw; }
                }
            }
        }
        public static bool ExecuteScalar(string sql )
        {
            using (SQLiteConnection conn = new SQLiteConnection(connectionString))
            {
                using (SQLiteCommand cmd = new SQLiteCommand(conn))
                {
                    try
                    {
                        conn.Open();
                        cmd.CommandText = sql;
                     
                        return  (Convert.ToInt32(cmd.ExecuteScalar()?.ToString()??"0")>0)?true:false;
                    }
                    catch (Exception) { throw; }
                }
            }
        }
        public static string ExecuteScalarStr(string sql)
        {
            using (SQLiteConnection conn = new SQLiteConnection(connectionString))
            {
                using (SQLiteCommand cmd = new SQLiteCommand(conn))
                {
                    try
                    {
                        conn.Open();
                        cmd.CommandText = sql;
                        return cmd.ExecuteScalar()?.ToString();
                    }
                    catch (Exception) { throw; }
                }
            }
        }
        /// <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>
        /// <exception cref="Exception"></exception>
        public static DataTable ExecuteQuery(string sql, params SQLiteParameter[]  parameters)
        {
            using (SQLiteConnection connection = new SQLiteConnection(connectionString))
            {
                using (SQLiteCommand command = new SQLiteCommand(sql, connection))
                {
                    if (parameters.Length != 0)
                    {
                        command.Parameters.AddRange(parameters);
                    }
                    SQLiteDataAdapter adapter = new SQLiteDataAdapter(command);
                    DataTable data = new DataTable();
                    try { adapter.Fill(data); }
                    catch (Exception) { throw; }
                    return data;
                }
            }
        }
        /// <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>
        /// <exception cref="Exception"></exception>
        public static SQLiteDataReader ExecuteReader(string sql, params SQLiteParameter[]  parameters)
        {
            SQLiteConnection connection = new SQLiteConnection(connectionString);
            SQLiteCommand command = new SQLiteCommand(sql, connection);
            try
            {
                if (parameters.Length != 0)
                {
                    command.Parameters.AddRange(parameters);
                }
                connection.Open();
                return command.ExecuteReader(CommandBehavior.CloseConnection);
            }
            catch (Exception) { throw; }
        }
        /// <summary>
        /// 查询数据库中的所有数据类型信息。
        /// </summary>
        /// <returns></returns>
        /// <exception cref="Exception"></exception>
        public static DataTable GetSchema()
        {
            using (SQLiteConnection connection = new SQLiteConnection(connectionString))
            {
                try
                {
                    connection.Open();
                    return connection.GetSchema("TABLES");
                }
                catch (Exception) { throw; }
            }
        }
    }

这里的SqliteConnectionstring连接字符串和SQL类似，Data Source改成对应的物理路径即可。

  <add name="SqliteConnectionstring" connectionString="Data  Source=D:/ProductsIndex.db"  providerName="System.Data.SqlClient" />

页面的调用：

string sql = string.Format(@" select * from T_BuildChildPath where ProductsCode like '%"  + PartCode + "%'");
DataView dv = SqliteHelper.ExecuteQuery(sql).DefaultView;