Microsoft Enterprise Library 5.0 系列(五) Data Access Application Block

企业库数据库访问模块通过抽象工厂模式,允许用户通过简单的配置选择不同的数据库作为程序的数据源,大大解决了切换数据库时带来的麻烦.因为我本机只安装了SQL Server 2005,所以在此只做SQL的演示,需要深究的朋友可以访问以下网站:

http://msdn.microsoft.com/en-us/library/ff664408%28v=PandP.50%29.aspx

 

企业库数据库访问模块的几大功能:

1.        最简单的功能,通过ExecuteNonQuery.方法执行SQL语句.

2.        执行ExecuteDataSet,返回DataSet类型的数据集.

3.        执行ExecuteScalar,获取返回的第一行第一列的信息.

4.        执行存储过程.

5.        通过代码实现事务.

6.        通过DataSet更新数据库.

7.        返回值XML化.

8.       将返回的数据对象化.

9.       异步访问数据库.

以上的功能我会在下面一一介绍 , 测试程序我已打包 , 大家可以 点击这里 下载 .

下面介绍如何使用Microsoft Enterprise Library 5.0中的数据库访问模块.

 

1.   首先创建一个测试数据库,创建数据库的SQL文件我打包在压缩包里了,大家可以点击上面的下载链接下载.执行完SQL文件后,可以看到我们创建好的TestDB数据库:

 

2.   下载安装好MicrosoftEnterprise Library 5.0,然后在运行EntLibConfig.exe,选择Blocks菜单 ,单击 AddDatabase Settings .

3.    配置好文件之后保存为App.config文件,并添加到创建好的应用程序中.并添加相应的引用,在此我不再多讲,大家下载我打包好的程序运行即可看到

 

 

4.      下面来介绍我在应用程序中实现的各个功能:

 

(1)     通过ExecuteNonQuery.方法执行SQL语句:      

    
    
    
    

     
     
     
     
     /// <summary>
/// 执行ExecuteNonQuery
/// </summary>
private void ExecuteNonQuery_Click(object sender, EventArgs e)
{
 db.ExecuteNonQuery(CommandType.Text, "INSERT INTO [College] ([CollegeID],[Name]) values (6,'体育学院')");
}
    
    
    
    

   

(2)    执行ExecuteDataSet,返回DataSet类型的数据集.

 

(3)    执行ExecuteScalar,返回第一行第一列的值.

    
    
    
    

     
     
     
     
     /// <summary>
/// 执行ExecuteScalar,返回第一行第一列的值
/// </summary>
/// <returns></returns>
private void ExecuteScalar_Click(object sender, EventArgs e)
{
 Database db = DatabaseFactory.CreateDatabase("ConnectionString");

 string sql = "select [Name] from College where [CollegeID] = 1";
 DbCommand dc = db.GetSqlStringCommand(sql);
 string str = "获取的学院名称为:" + (string)db.ExecuteScalar(dc);
 MessageBox.Show(str);

 sql = "select [CollegeID] from College where [CollegeID] = 1";
 dc = db.GetSqlStringCommand(sql);
 str = "获取的学院ID为:" + (int)db.ExecuteScalar(dc);
 MessageBox.Show(str);
}
    
    
    
    

 

 

 

 

(4)    执行存储过程.

    
    
    
    

     
     
     
     
     /// <summary>
/// 执行存储过程
/// </summary>
private void StoredProcCommand_Click(object sender, EventArgs e)
{
 DbCommand dc = db.GetStoredProcCommand("usp_College_LoadByID");

 db.AddInParameter(dc, "@CollegeID", System.Data.DbType.Int32, 5);

 dataGridView1.DataSource = db.ExecuteDataSet(dc).Tables[0];
}
    
    
    
    

 

 

(5)    通过代码实现事务.

    
    
    
    

     
     
     
     
     /// <summary>
/// 事务
/// </summary>
private void Transaction_Click(object sender, EventArgs e)
{
 DbCommand dc1 = db.GetStoredProcCommand("usp_College_Insert");

 db.AddInParameter(dc1, "@CollegeID", DbType.Int32, 7);
 db.AddInParameter(dc1, "@Name", DbType.String, "文旅学院");

 DbCommand dc2 = db.GetStoredProcCommand("usp_College_Insert");

 db.AddInParameter(dc2, "@CollegeID", DbType.Int32, 7);
 db.AddInParameter(dc2, "@Name", DbType.String, "化工学院");

 using (DbConnection conn = db.CreateConnection())
 {
 conn.Open();
 DbTransaction trans = conn.BeginTransaction();

 try
 {
 //添加一个ID为7的学院
 db.ExecuteNonQuery(dc1, trans);

 //添加一个ID为7的学院,主键重复,事务将回滚
 db.ExecuteNonQuery(dc2, trans);

 //提交事务.
 trans.Commit();
 }
 catch
 {
 //回滚
 trans.Rollback();
 }
 conn.Close();
 }

 //查看数据库,数据未被添加,说明事务已回滚
 ExecuteDataSet_Click(null, null);
}
    
    
    
    

 

 

 

(6)    通过DataSet更新数据库.

    
    
    
    

     
     
     
     
     /// <summary>
/// 通过DataSet更新数据库
/// </summary>
private void DataSetUpdate_Click(object sender, EventArgs e)
{
 DataSet productsDataSet = new DataSet();

 string sql = "Select * From College";
 DbCommand cmd = db.GetSqlStringCommand(sql);

 string CollegeTableName = "College";

 //恢复原始数据
 db.LoadDataSet(cmd, productsDataSet, CollegeTableName);

 //获取数据表格
 DataTable dTable = productsDataSet.Tables[CollegeTableName];

 //添加一个新信息入DataSet中
 DataRow addedRow = dTable.Rows.Add(new object[] { 8, "外国语学院" });

 //修改一个原有数据
 dTable.Rows[0]["Name"] = "国教院";

 //提供插入,更新,删除存储过程
 DbCommand insertCommand = db.GetStoredProcCommand("usp_College_Insert");
 db.AddInParameter(insertCommand, "@CollegeID", DbType.Int32, "CollegeID", DataRowVersion.Current);
 db.AddInParameter(insertCommand, "@Name", DbType.String, "Name", DataRowVersion.Current);

 DbCommand deleteCommand = db.GetStoredProcCommand("usp_College_Delete");
 db.AddInParameter(deleteCommand, "@CollegeID", DbType.Int32, "CollegeID", DataRowVersion.Current);

 DbCommand updateCommand = db.GetStoredProcCommand("usp_College_Update");
 db.AddInParameter(updateCommand, "@CollegeID", DbType.Int32, "CollegeID", DataRowVersion.Current);
 db.AddInParameter(updateCommand, "@Name", DbType.String, "Name", DataRowVersion.Current);

 //通过DataSet更新数据库
 int rowsAffected = db.UpdateDataSet(productsDataSet, CollegeTableName, insertCommand, updateCommand, deleteCommand,
 Microsoft.Practices.EnterpriseLibrary.Data.UpdateBehavior.Standard);

 MessageBox.Show("影响的行数:" + rowsAffected);
}
    
    
    
    

 

 

 

(7)    返回值XML化.

    
    
    
    

     
     
     
     
     /// <summary>
/// 返回值XML化
/// </summary>
private void ReturnXML_Click(object sender, EventArgs e)
{
 //使用"FOR XML AUTO"参数使得SQL返回XML格式的信息
 SqlDatabase sqldb = (SqlDatabase)DatabaseFactory.CreateDatabase("ConnectionString");

 DbCommand cmd = sqldb.GetSqlStringCommand("SELECT * FROM College FOR XML AUTO");
 IEnumerable<string> productList;

 using (var reader = sqldb.ExecuteXmlReader(cmd))
 {
 if (reader.IsStartElement())
 {
 var root = (XElement)XNode.ReadFrom(reader);
 productList = root.Elements("CollegeID")
 .Attributes("Name")
 .Select(a => a.Value).ToArray();

 MessageBox.Show(((XElement)root).ToString());
 }
 }
}
    
    
    
    

 

 

 

(8)    将返回的数据对象化.

    
    
    
    

     
     
     
     
     /// <summary>
/// DataAsObject
/// </summary>
private void DataAsObject_Click(object sender, EventArgs e)
{
 //将返回的数据对象化
 var results = db.ExecuteSprocAccessor<College>("usp_College_LoadAll");

 MessageBox.Show(results.ElementAt(0).ToString());
}
    
    
    
    

 

 

 

(9)    异步访问数据库.

    
    
    
    

     
     
     
     
     /// <summary>
/// 异步访问数据库
/// </summary>
private void Async_Click(object sender, EventArgs e)
{
 //创建新的数据库连接,属性必须添加:Asynchronous Processing=true
 String connectionString = @"server=(local); database=TestDB; Integrated Security=true; Asynchronous Processing=true";
 Database Sqldb = new SqlDatabase(connectionString);
 DbCommand cmd = Sqldb.GetStoredProcCommand("usp_College_LoadbyID");
 Sqldb.AddInParameter(cmd, "@CollegeID", DbType.Int32, 1);

 try
 {
 IAsyncResult result = Sqldb.BeginExecuteReader(cmd, MyEndExecuteCallback, Sqldb);
 }
 catch (Exception ex)
 {
 MessageBox.Show(ex.ToString());
 }
}

//当获取完毕执行该函数
private void MyEndExecuteCallback(IAsyncResult result)
{
 try
 {
 Database Sqldb = (Database)result.AsyncState;
 IDataReader reader = db.EndExecuteReader(result);

 College c = new College((int)reader[0], (string)reader[1]);

 MessageBox.Show(c.ToString());
 }
 catch(Exception ex)
 {
 MessageBox.Show(ex.ToString());
 }
}
    
    
    
    

 

    
    
    
    

     
     
     
     
     /// <summary>
/// 执行ExecuteDataSet，返回College列表
/// </summary>
/// <returns></returns>
private void ExecuteDataSet_Click(object sender, EventArgs e)
{
 string sql = "select * from College";
 DbCommand dw = db.GetSqlStringCommand(sql);

 dataGridView1.DataSource = db.ExecuteDataSet(dw).Tables[0];
}