Enterprise Library2.0的数据访问应用常用操作-技术开发专区

Enterprise Library2.0的数据访问应用常用操作

作者：佚名编辑：晓熊 2007-05-30 09:43

三．常见功能
1．创建Database对象
创建一个默认的Database对象
Database dbSvc = DatabaseFactory.CreateDatabase();
默认的数据库在配置文件中：
<dataConfiguration defaultDatabase="DataAccessQuickStart" />
创建一个实例Database对象

// Use a named database instance that refers to an arbitrary database type,
// which is determined by configuration information.
Database myDb = DatabaseFactory.CreateDatabase("DataAccessQuickStart");
创建一个具体的类型的数据库对象

// Create a SQL database.
SqlDatabase dbSQL = DatabaseFactory.CreateDatabase("DataAccessQuickStart") as SqlDatabase;
2．创建DbCommand对象

静态的SQL语句创建一个DbCommand

Database db = DatabaseFactory.CreateDatabase();
string sqlCommand = "Select CustomerID, LastName, FirstName From Customers";
DbCommand dbCommand = db.GetSqlStringCommand(sqlCommand);
存储过程创建一个DbCommand

Database db = DatabaseFactory.CreateDatabase();
DbCommand dbCommand = db.GetStoredProcCommand("GetProductsByCategory");
3．管理对象

当连接对象打开后，不需要再次连接

Database db = DatabaseFactory.CreateDatabase();
string sqlCommand = "Select ProductID, ProductName From Products";
DbCommand dbCommand = db.GetSqlStringCommand(sqlCommand);
// No need to open the connection; just make the call. 
DataSet customerDataSet = db.ExecuteDataSet(dbCommand);
使用Using及早释放对象

Database db = DatabaseFactory.CreateDatabase();
DbCommand dbCommand = db.GetSqlStringCommand("Select Name, Address From Customers");
using (IDataReader dataReader = db.ExecuteReader(dbCommand))
...{
// Process results 
}

4．参数处理

Database类提供了如下的方法，用于参数的处理：
AddParameter. 传递参数给存储过程
AddInParameter. 传递输入参数给存储过程
AddOutParameter. 传递输出参数给存储过程
GetParameterValue. 得到指定参数的值
SetParameterValue. 设定参数值

使用示例如下：

Database db = DatabaseFactory.CreateDatabase();
string sqlCommand = "GetProductDetails";
DbCommand dbCommand = db.GetStoredProcCommand(sqlCommand);
db.AddInParameter(dbCommand, "ProductID", DbType.Int32, 5);
db.AddOutParameter(dbCommand, "ProductName", DbType.String, 50);
db.AddOutParameter(dbCommand, "UnitPrice", DbType.Currency, 8);


Database db = DatabaseFactory.CreateDatabase();
DbCommand insertCommand = db.GetStoredProcCommand("AddProduct");
db.AddInParameter(insertCommand, "ProductName", DbType.String, "ProductName", DataRowVersion.Current);
db.AddInParameter(insertCommand, "CategoryID", DbType.Int32, "CategoryID", DataRowVersion.Current);
db.AddInParameter(insertCommand, "UnitPrice", DbType.Currency, "UnitPrice", DataRowVersion.Current);

四．使用场景
DAAB2.0是对ADO.NET2.0的补充，它允许你使用相同的数据访问代码来支持不同的数据库，您通过改变配置文件就在不同的数据库之间切换。目前虽然只提供SQLServer和Oracle的支持，但是可以通过GenericDatabase和ADO.NET 2.0下的DbProviderFactory对象来增加对其他数据库的支持。如果想要编写出来的数据库访问程序具有更好的移植性，则DAAB2.0是一个不错的选择，但是如果您想要针对特定数据库的特性进行编程，就要用ADO.NET了。

参考：Enterprise Libaray –January 2006帮助文档及QuickStart

动手试一下SQL和ACCESS数据库自由切换的方法，因俺平时的习惯是使用vb.net写东西，所以只写出vb.net的代码出来，有兴趣的自己改成C#好了，看以下html代码：

<%...@ Page Language="VB" AutoEventWireup="false" CodeFile="sql.aspx.vb" Inherits="sql" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>web3.cn——SQL、Access数据库自由切换</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False">
<Columns>
<asp:BoundField DataField="id" HeaderText="id" SortExpression="id" >
<HeaderStyle BackColor="Silver" />
</asp:BoundField>
<asp:BoundField DataField="provinceID" HeaderText="provinceID" SortExpression="provinceID" >
<HeaderStyle BackColor="Silver" />
</asp:BoundField>
<asp:BoundField DataField="province" HeaderText="provinceID" SortExpression="province" >
<HeaderStyle BackColor="Silver" />
</asp:BoundField>
</Columns>
</asp:GridView>
</div>
</form>
</body>
</html>
vb.net代码：
Imports System.Data
Imports Microsoft.Practices.EnterpriseLibrary.Data
Imports system.Data.Common
Imports System.Data.Odbc
Partial Class sql_accessClass sql_access
Inherits System.Web.UI.Page
Dim sys As New WebService
Protected Sub Page_Load()Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If Not Page.IsPostBack Then
BindGrid()
End If
End Sub
Sub BindGrid()Sub BindGrid()
Dim dv As DataView
dv = GetList_Access().DefaultView
GridView1.DataSource = dv
GridView1.DataBind()
End Sub
'列表 
Public Function GetList_SQL()Function GetList_SQL() As DataTable
Dim db As Database = DatabaseFactory.CreateDatabase()
Dim sqlCommand As String = "select * FROM province ORDER BY id desc"
'要对数据源执行的 SQL 语句或存储过程。 
Dim dbCommand As DbCommand = db.GetSqlStringCommand(sqlCommand)
Return db.ExecuteDataSet(dbCommand).Tables(0)
End Function
'列表 
Public Function GetList_Access()Function GetList_Access() As DataTable
Dim db As Database = New GenericDatabase("Driver={Microsoft Access Driver (*.mdb)};Dbq=D:vs2005dbdb.mdb;Uid=sa;Pwd=sa;", OdbcFactory.Instance)
Dim sqlCommand As String = "select * FROM province ORDER BY id desc"
'要对数据源执行的 SQL 语句或存储过程。 
Dim dbCommand As DbCommand = db.GetSqlStringCommand(sqlCommand)
Return db.ExecuteDataSet(dbCommand).Tables(0)
End Function

以上代码不多，应该明白了吧，呵呵，只要把“dv = GetList_Access().DefaultView”换成“dv = GetList_SQL().DefaultView”即可换成了SQL的数据库了，简单吧。这里只给出一个思路，就看大家封装起来成更加简单易用的咯。

第1页：新版改进第2页：使用示例第3页：DataAccessQuickStart示例分析第4页：常见功能

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