存储过程和使用程序块更新数据
该练习将示范如何用数据访问应用程序调用存储过程,并使用强类型的DataSet来更新数据。
练习2:存储过程和使用程序块更新数据
该练习将示范如何用数据访问应用程序调用存储过程,并使用强类型的DataSet来更新数据。
第一步
打开DataEx2.sln项目,默认的安装路径应该为C:\Program Files\Microsoft Enterprise Library January 2006\labs\cs\Data Access\exercises\ex02\begin,并编译。
第二步 在QuickStarts数据库中添加Categories数据表
运行批处理文件SetUpEx02.bat,它默认的路径安装路径为C:\Program Files\Microsoft Enterprise Library January 2006\labs\cs\Data Access\exercises\ex02\DbSetup,默认的服务器实例为(local)\SQLEXPRESS,如果需要修改,用记事本打开SetUpEx02.bat,修改为自己的德数据库服务器实例。执行后将会在数据库中创建Categories数据表和存储过程GetCategories,并会在表中插入一些数据。
第三步 回顾应用程序
在解决方案管理器中,选中MainForm.cs文件,选择 View | Designer 菜单,应用程序主要是选择一个特定的Category,它将会加载该类别下的所有产品,允许我们作一些修改并保存。
第四步 实现数据的读取
1.在解决方案管理器中选择MainForm.cs,选择View | Code 菜单命令,在代码中添加如下命名空间,在这之前请先添加对Data和Common两个程序集的引用,可以参考练习一。
using Microsoft.Practices.EnterpriseLibrary.Data;
2.在窗体中加入如下私有域,后面将会在多个地方用到该数据库实例。
private Database _db = DatabaseFactory.CreateDatabase("QuickStarts Instance");
3.在MainForm_Load方法中加入如下代码
private void MainForm_Load(object sender, System.EventArgs e)
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{
this.cmbCategory.Items.Clear();
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// TODO: Use a DataReader to retrieve Categories
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using (IDataReader dataReader = _db.ExecuteReader("GetCategories"))
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{
// Processing code
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while (dataReader.Read())
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{
Category item = new Category(
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dataReader.GetInt32(0),
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dataReader.GetString(1),
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dataReader.GetString(2));
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this.cmbCategory.Items.Add(item);
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}
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}
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if (this.cmbCategory.Items.Count > 0)
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this.cmbCategory.SelectedIndex = 0;
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}
重载的方法Database.ExecuteReader,有一个字符串类型的参数,通过它来指定存储过程的名称,在这里我们不用做任何数据库连接方面的管理,但是在DataReader使用完毕后释放很重要,这些都会由上面的代码来完成,当DataReader释放后,数据库连接也将被关闭。
4.在cmbCategory_SelectedIndexChanged方法中加入如下代码,它将根据我们选择的类别来读取对应的Product的集合。
private void cmbCategory_SelectedIndexChanged(object sender, System.EventArgs e)
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{
this.dsProducts.Clear();
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Category selectedCategory = (Category)this.cmbCategory.SelectedItem;
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if (selectedCategory == null)
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return;
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// TODO: Retrieve Products by Category
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_db.LoadDataSet(
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"GetProductsByCategory",
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this.dsProducts,
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
new string[]
{ "Products" },
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selectedCategory.CategoryId);
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}
在数据访问应用程序块中Database类提供了两个关于DataSet的方法ExecuteDataSet和LoadDataSet。ExecuteDataSet返回一个新的DataSet而LoadDataSet则返回一个已经存在的DataSet。
第五步 实现数据的更新
在btnSave_Click方法中加入如下代码,将会把所有的任何改动更新到数据库中去。
private void btnSave_Click(object sender, System.EventArgs e)
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
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{
// TODO: Use the DataSet to update the Database
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System.Data.Common.DbCommand insertCommand = null;
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insertCommand = _db.GetStoredProcCommand("HOLAddProduct");
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_db.AddInParameter(insertCommand, "ProductName",
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DbType.String, "ProductName", DataRowVersion.Current);
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_db.AddInParameter(insertCommand, "CategoryID",
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DbType.Int32, "CategoryID", DataRowVersion.Current);
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_db.AddInParameter(insertCommand, "UnitPrice",
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
DbType.Currency, "UnitPrice", DataRowVersion.Current);
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System.Data.Common.DbCommand deleteCommand = null;
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deleteCommand = _db.GetStoredProcCommand("HOLDeleteProduct");
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_db.AddInParameter(deleteCommand, "ProductID",
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DbType.Int32, "ProductID", DataRowVersion.Current);
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_db.AddInParameter(deleteCommand, "LastUpdate",
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
DbType.DateTime, "LastUpdate", DataRowVersion.Original);
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System.Data.Common.DbCommand updateCommand = null;
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updateCommand = _db.GetStoredProcCommand("HOLUpdateProduct");
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_db.AddInParameter(updateCommand, "ProductID",
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
DbType.Int32, "ProductID", DataRowVersion.Current);
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_db.AddInParameter(updateCommand, "ProductName",
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
DbType.String, "ProductName", DataRowVersion.Current);
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
_db.AddInParameter(updateCommand, "CategoryID",
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
DbType.Int32, "CategoryID", DataRowVersion.Current);
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
_db.AddInParameter(updateCommand, "UnitPrice",
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
DbType.Currency, "UnitPrice", DataRowVersion.Current);
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
_db.AddInParameter(updateCommand, "LastUpdate",
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
DbType.DateTime, "LastUpdate", DataRowVersion.Current);
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
int rowsAffected = _db.UpdateDataSet(
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
this.dsProducts,
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
"Products",
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
insertCommand,
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
updateCommand,
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
deleteCommand,
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
UpdateBehavior.Standard);
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
}
在更新一个数据库时,需要对DataTable的列和存储过程中的参数之间作一个映射,重载的方法UpdateDataSet,它通过数据访问程序块自动执行更新事务,在这里UpdateBehaviour是可以设置的,它有三种类型:Transactional,Continue,Standard。
第六步 运行应用程序
选择Debug | Start Without Debugging菜单命令并运行应用程序,在Category下拉框中选择一个类别,观察如何加载和保存数据。
更多Enterprise Library的文章请参考《Enterprise Library系列文章》