Windows Phone 7开发中使用SQL CE数据库实例

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在WindowsPhone中有时候我们会一些数据的存储，这个时候我们有两种选择，一种是选择存在的独立存储文件中，一种是存储在数据库中。存储在独立存储文件中，这个相信很多用都会使用，这里不作为重点，本文主要讲一下在WindowsPhone中使用数据库SQL CE。

下面开始一步一步的带领大家实现在WindowsPhone 中使用SQL CE数据库。（该示例引自WindowsPhone 7应用开发）

一、首先，我们需要创建一个EmployeeTable类，映射为数据库中的Employee表

如下：

在创建之前需要添加引用：System.Data.Linq；

同时引入命名空间：using System.Data.Linq.Mapping;

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[Table]//特性标识该类为映射为数库中的表
//该类实现了INotifyPropertyChanged和INotifyPropertyChanging接口
   public class EmployeeTable:INotifyPropertyChanged,INotifyPropertyChanging
   {
       private int _employeeId;
       //将EmployeeID映射为表的主键，特性Column里的含义分别为：主键，自增，int型不为空，不为空等
       [Column(IsPrimaryKey = true, IsDbGenerated = true,DbType = "INT NOT NULL Identity", CanBeNull = false, AutoSync = AutoSync.OnInsert)]
       public int EmployeeID
       {
           get
           {
               return _employeeId;
           }
           set
           {
               if (_employeeId != value)
               {
                   NotifyPropertyChanging("EmployeeID");
                   _employeeId = value;
                   NotifyPropertyChanged("EmployeeID");
               }
           }
       }
       private string _employeeName;
       [Column]//EmployeeName属性为表中EmployeeName字段
       public string EmployeeName
       {
           get
           {
               return _employeeName;
           }
           set
           {
               if (_employeeName != value)
               {
                   NotifyPropertyChanging("EmployeeName");
                   _employeeName = value;
                   NotifyPropertyChanged("EmployeeName");
               }
           }
       }
       private string _employeeDesc;
       [Column]//将EmployeeDesc属性映射为表中EmployeeDesc字段
       public string EmployeeDesc
       {
           get
           {
               return _employeeDesc;
           }
           set
           {
               if (_employeeDesc != value)
               {
                   NotifyPropertyChanging("EmployeeDesc");
                   _employeeDesc = value;
                   NotifyPropertyChanged("EmployeeDesc");
               }
           }
       }
       //定义PropertyChanged事件用来通知页面，表字段数据发生了改变
       public event PropertyChangedEventHandler PropertyChanged;
       private void NotifyPropertyChanged(string propertyName)
       {
           if (PropertyChanged != null)
           {
               PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
           }
       }
       //定义PropertyChanging事件通知数据上下文表的字段数据将要发生改变
       public event PropertyChangingEventHandler PropertyChanging;
       private void NotifyPropertyChanging(string propertyname)
       {
           if (PropertyChanging != null)
           {
               PropertyChanging(this, new PropertyChangingEventArgs(propertyname));
           }
       }
   }

通过以上的这些操作，我们已经基本上完成了Employee表的创建，映射为数据库中的EmployeeTable表

二、下面我们来新建一个EmployeeDataContext.cs类文件，创建数据库的DataContent，该类继承自DataContent,在该类中定义连接字符串，如下：

首先需要引入命名空间：using system.data.Linq;

public class EmployeeDataContext:DataContext
    {
        //数据库连接字符串
        public static string DBConnectionString = "Data Source=isostore:/Employee.sdf";
        //传递数据库连接字符串到DataContext基类
        public EmployeeDataContext(string connectionString):base(connectionString)
        {
        }
        //定义员工信息表
        public Table<EmployeeTable> Employees;
    }

三、创建EmployeeCollection类，该类的主要作用为页面数据绑定的集合。如下：

//绑定页面，进行显示用

public class EmployeeCollection:INotifyPropertyChanged
{
    //用于通知属性的改变
        public event PropertyChangedEventHandler PropertyChanged;
        public void NotifyPropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this,new PropertyChangedEventArgs (propertyName));
            }
        }
        private ObservableCollection<EmployeeTable> _employeeTables;

//创建EmployeeTables属性用来绑定页面数据

public ObservableCollection<EmployeeTable> EmployeeTables
        {
            get
            {
                return _employeeTables;
            }
            set
            {
                if (_employeeTables != value)
                {
                    _employeeTables = value;
                    NotifyPropertyChanged("EmployeeTables");
                }
            }
        }
    }

四、这样一个完整的数据库就创建完毕了，那么我们该如何使用呢？一般的情况下我们都是在程序启动的时候加载数据库，为此我们可以在App.xaml文件的Launching事件中做如下处理：

using (EmployeeDataContext db=new EmployeeDataContext(EmployeeDataContext.DBConnectionString))
           {
                if (db.DatabaseExists() == false)
                {
                    db.CreateDatabase();
                }
            }

五、下面做一个实例进行演示：

页面布局如下：

<phone:PhoneApplicationPage.Resources>
        <DataTemplate x:Key="listitem">
            <Grid HorizontalAlignment="Stretch" Width="440">
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="50"/>
                    <ColumnDefinition Width="*"/>
                    <ColumnDefinition Width="100"/>
                 </Grid.ColumnDefinitions>
                <TextBlock Text="{Binding EmployeeName}" FontSize="{StaticResource PhoneFontSizeLarge}" Grid.Column="1" <BR>VerticalAlignment="Center"/>
                <Button Grid.Column="2" Click="deleteButton_Click" x:Name="deleteButton" BorderThickness="0" Margin="0" Content="删除" ></Button>
                <Button Grid.Column="1" x:Name="editButton" Click="editButton_Click"BorderThickness="0" Margin="209,0,81,0" Content="编辑" <BR>Grid.ColumnSpan="2"></Button>
            </Grid>
        </DataTemplate>
    </phone:PhoneApplicationPage.Resources>
    
    <Grid x:Name="LayoutRoot" Background="Transparent">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        
        <StackPanel x:Name="TitlePanel" Grid.Row="0" Margin="12,17,0,28">
            <TextBlock x:Name="ApplicationTitle" Text="我的应用程序" Style="{StaticResource PhoneTextNormalStyle}"/>
            <TextBlock x:Name="PageTitle" Text="EmployeeShow" Margin="9,-7,0,0" Style="{StaticResource PhoneTextTitle1Style}"/>
        </StackPanel>
        
        <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
            <TextBlock FontSize="24" Name="textBlock1" Text="员工名字：
                       " Margin="12,22,330,544" />
            <TextBlock FontSize="24" Margin="12,93,330,473" Name="textBlock2" Text="简介：" />
            <TextBox Height="72" HorizontalAlignment="Left" Margin="132,6,0,0" Name="txtname" Text=""
                    VerticalAlignment="Top" Width="281" />
            <TextBox Height="72" HorizontalAlignment="Left" Margin="132,78,0,0" Name="txtdesc" Text=""
                    VerticalAlignment="Top" Width="281" />
            <Button Content="保存" Height="72" HorizontalAlignment="Left" Margin="243,150,0,0" Name="button2"
                    VerticalAlignment="Top" Width="160" Click="button2_Click" />
            <ListBox Height="293" HorizontalAlignment="Left" Margin="-12,228,0,0" Name="listBox1" VerticalAlignment="Top"
                    Width="460" ItemTemplate="{StaticResource listitem}" />
        </Grid>
    </Grid>
</phone:PhoneApplicationPage>

.cs页的处理代码如下：

public partial class EmployeeShow : PhoneApplicationPage
    {
        //创建DataContext用于操作独立的数据库
        private EmployeeDataContext employeeDB;
        private EmployeeCollection employeeCol = new EmployeeCollection();

  public EmployeeShow()
        {
            InitializeComponent();
    //创建EmployeeDataContext实例
    employeeDB = new EmployeeDataContext(EmployeeDataContext.DBConnectionString);
            var employeeInDB = from EmployeeTable employee in employeeDB.Employees
                               select employee;
//为页面创建数据绑定源
employeeCol.EmployeeTables = new System.Collections.ObjectModel.ObservableCollection<EmployeeTable>(employeeInDB);
            listBox1.ItemsSource = employeeCol.EmployeeTables;
        }

//删除信息

private void deleteButton_Click(object sender, RoutedEventArgs e)
        {
            var button = sender as Button;
            if (button != null)
            {
                EmployeeTable edelete = button.DataContext as EmployeeTable;
                //
                employeeCol.EmployeeTables.Remove(edelete);
                employeeDB.Employees.DeleteOnSubmit(edelete);
                employeeDB.SubmitChanges();
            }
        }

//保存信息

private void button2_Click(object sender, RoutedEventArgs e)
        {
            if (txtname.Text != "" && txtdesc.Text != "")
            {
                //编辑状态
                if (State.Count > 0 && State["employee"] != null)
                {
                    EmployeeTable employee = (EmployeeTable)State["employee"];
                    employee.EmployeeName = txtname.Text;
                    employee.EmployeeDesc = txtdesc.Text;
                    employeeDB.SubmitChanges();
                    employeeCol.EmployeeTables.Add(employee);
                    State["employee"] = null;
                }
                Else//添加新的信息
                {
                    EmployeeTable newEmployee = new EmployeeTable
                    {
                        EmployeeName = txtname.Text,
                        EmployeeDesc = txtdesc.Text
                    };
                    employeeCol.EmployeeTables.Add(newEmployee);
                    employeeDB.Employees.InsertOnSubmit(newEmployee);
                    employeeDB.SubmitChanges();
                    txtname.Text = "";
                    txtdesc.Text = "";
                }
                listBox1.ItemsSource = employeeCol.EmployeeTables;
            }
            else
            {
                MessageBox.Show("姓名和简介不能为空！");
            }
        }

//编辑信息

private void editButton_Click(object sender, RoutedEventArgs e)
     {
         var button = sender as Button;
         if (button != null)
         {
             EmployeeTable eedit = button.DataContext as EmployeeTable;
             txtname.Text = eedit.EmployeeName;
             txtdesc.Text = eedit.EmployeeDesc;
             State["employee"] = eedit;
             employeeCol.EmployeeTables.Remove(eedit)；
         }
     }
}

效果如图：