我在控制台应用程序中有以下C＃代码。

每当我调试应用程序并运行query1（它将向数据库中插入新值）然后运行query2（将显示数据库中的所有条目）时，都可以清楚地看到我插入的新条目。但是，当我关闭应用程序并检查数据库中的表（在Visual
Studio中）时，它消失了。我不知道为什么它没有保存。

using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data.SqlServerCe;
using System.Data;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                string fileName = "FlowerShop.sdf";
                string fileLocation = "|DataDirectory|\\";
                DatabaseAccess dbAccess = new DatabaseAccess();
                dbAccess.Connect(fileName, fileLocation);

                Console.WriteLine("Connected to the following database:\n"+fileLocation + fileName+"\n");
                string query = "Insert into Products(Name, UnitPrice, UnitsInStock) values('NewItem', 500, 90)";
                string res = dbAccess.ExecuteQuery(query);
                Console.WriteLine(res);

                string query2 = "Select * from Products";
                string res2 = dbAccess.QueryData(query2);
                Console.WriteLine(res2);
                Console.ReadLine();
            }
            catch (Exception e)
            {
                Console.WriteLine(e);
                Console.ReadLine();
            }
        }
    }

    class DatabaseAccess
    {
        private SqlCeConnection _connection;

        public void Connect(string fileName, string fileLocation)
        {
            Connect(@"Data Source=" + fileLocation + fileName);
        }

        public void Connect(string connectionString)
        {
            _connection = new SqlCeConnection(connectionString);
        }

        public string QueryData(string query)
        {
            _connection.Open();
            using (SqlCeDataAdapter da = new SqlCeDataAdapter(query, _connection))
            using (DataSet ds = new DataSet("Data Set"))
            {
                da.Fill(ds);
                _connection.Close();
                return ds.Tables[0].ToReadableString(); // a extension method I created
            }
        }

        public string ExecuteQuery(string query)
        {
            _connection.Open();
            using (SqlCeCommand c = new SqlCeCommand(query, _connection))
            {
                int r = c.ExecuteNonQuery();
                _connection.Close();
                return r.ToString();
            }
        } 
    }

编辑：忘记提及我正在使用SQL Server Compact Edition 4和VS2012 Express。