WindowsPhone 中SQL CE数据库的使用

       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;

 [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" 
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" 
Grid.ColumnSpan="2"></Button>
            </Grid>
        </DataTemplate>
    </phone:PhoneApplicationPage.Resources>
    <!--LayoutRoot 是包含所有页面内容的根网格-->
    <Grid x:Name="LayoutRoot" Background="Transparent">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        <!--TitlePanel 包含应用程序的名称和页标题-->
        <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>
        <!--ContentPanel - 在此处放置其他内容-->
        <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：

 

 

好了，到这里我们已经基本上实现了在WindowsPhone手机中使用SQLCE数据库了，希望可以对朋友们有所帮助。