Access数据库创建、使用

public DataSet Query(string strSql)
        {
            using (OleDbConnection conn = new OleDbConnection(ConnectionString))
            {
                DataSet ds = new DataSet();
                try
                {
                    conn.Open();
                    OleDbDataAdapter command = new OleDbDataAdapter(strSql, conn);
                    command.Fill(ds, "ds");
                }
                catch (System.Data.SqlClient.SqlException ex)
                {
                    throw;
                }

                return ds;
            }
        }

        public  int ExecuteSql(string strSql)
        {
            using (OleDbConnection conn = new OleDbConnection(ConnectionString))
            {
                using (OleDbCommand cmd = new OleDbCommand(strSql, conn))
                {
                    try
                    {
                        conn.Open();
                        int rows = cmd.ExecuteNonQuery();
                        return rows;
                    }
                    catch (System.Data.SqlClient.SqlException e)
                    {
                        conn.Close();
                        throw e;
                    }
                }
            }
        }

        public object GetSingle(string strSql)
        {
            using (OleDbConnection conn = new OleDbConnection(ConnectionString))
            {
                using (OleDbCommand cmd = new OleDbCommand(strSql, conn))
                {
                    try
                    {
                        conn.Open();
                        object obj = cmd.ExecuteScalar();
                        if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
                        {
                            return null;
                        }
                        else
                        {
                            return obj;
                        }
                    }
                    catch (System.Data.SqlClient.SqlException e)
                    {
                        conn.Close();
                        throw e;
                    }
                }
            }
        }