Enterprise Library: Data Access Application Block使用向导，Part 2

本文是前一篇posting《Enterprise Library: Data Access Application Block使用向导，Part 1》的Part 2，主要演示使用Data Access Application Block (Enterprise Library)的代码部分。

Data Access Application Block使用向导：

1．增加对Microsoft.Practices.EnterpriseLibrary.Data.dll和Microsoft.Practices.EnterpriseLibrary.Configuration.dll的引用，并在代码在添加：

using Microsoft.Practices.EnterpriseLibrary.Data;

 

2．调用代码示例：

(1) ExecuteDataSet方法

Database db = DatabaseFactory.CreateDatabase();

DataSet dsCustomers = db.ExecuteDataSet(CommandType.Text, "Select * From Customers" );

customerGrid.DataSource = dsCustomers.Tables[0];

 

(2) ExecuteReader方法

Database db = DatabaseFactory.CreateDatabase();

 

string sqlCommand = "Select top 5 * From Customers";

DBCommandWrapper dbCommandWrapper = db.GetSqlStringCommandWrapper(sqlCommand);

 

StringBuilder readerData = new StringBuilder();

 

using (IDataReader dataReader = db.ExecuteReader(dbCommandWrapper))

{

while (dataReader.Read())

{

readerData.Append(dataReader["ContactName"]);

readerData.Append(Environment.NewLine);

}

}

 

txtResult.Text = readerData.ToString();

为了执行SQL语句，上述代码使用GetSqlStringCommandWrapper方法创建合适command wrapper对象，然后作为参数传递给ExecuteReader方法。

 

(3) ExecuteNonQuery方法

Database db = DatabaseFactory.CreateDatabase();

 

string sqlCommand = "getProductDetails";

DBCommandWrapper dbCommandWrapper = db.GetStoredProcCommandWrapper(sqlCommand);

 

// Add paramters

int productID=1;

// Input parameters can specify the input value

dbCommandWrapper.AddInParameter("@ProductID", DbType.Int32, productID);

// Output parameters specify the size of the return data

dbCommandWrapper.AddOutParameter("@ProductName", DbType.String, 40);

dbCommandWrapper.AddOutParameter("@UnitPrice", DbType.Currency, 8);

dbCommandWrapper.AddOutParameter("@QtyPerUnit", DbType.String, 20);

 

db.ExecuteNonQuery(dbCommandWrapper);

 

// Row of data is captured via output parameters

string results = string.Format(CultureInfo.CurrentCulture, "{0}, {1}, {2:C}, {3} ",

      dbCommandWrapper.GetParameterValue("@ProductID"),

      dbCommandWrapper.GetParameterValue("@ProductName"),

      dbCommandWrapper.GetParameterValue("@UnitPrice"),

      dbCommandWrapper.GetParameterValue("@QtyPerUnit"));

 

txtResult.Text = results;

为了执行存储过程，上述代码使用GetStoredProcCommandWrapper方法创建合适的command wrapper对象，然后作为参数传递给ExecuteNonQuery方法。

 

(4) ExecuteScalar方法

Database db = DatabaseFactory.CreateDatabase();

 

string sqlCommand = "GetProductName";

int productID=1;

DBCommandWrapper dbCommandWrapper = db.GetStoredProcCommandWrapper(sqlCommand, productID);

 

// Retrieve ProdcutName. ExecuteScalar returns an object, so

// we cast to the correct type (string).

string productName = (string) db.ExecuteScalar(dbCommandWrapper);

 

txtResult.Text = productName;

 

Demo程序界面如下（注意在项目属性窗口中设置Post-build Event Command Line属性值：copy "$(ProjectDir)*.config" "$(TargetDir)"）：

 

***

作者：Rickie Lee (rickieleemail#yahoo.com)

本文参考Enterprise Library: Data Access Application Block Quick Start范例，简单编写一个DEMO。

 

References:

1. Enterprise Library: Data Access Application Block Quick Start

2. Rickie, Microsoft patterns & practices Enterprise Library January 2005 [中文稿], http://www.cnblogs.com/rickie/archive/2005/01/30/99443.html

3. Rickie, Enterprise Library released! http://www.cnblogs.com/rickie/archive/2005/01/29/99106.html