为了方便的访问数据,微软自己封装了一个数据访问模块,即DataAccessApplicationBlock.通过它,我们用来访问数据库的编码量大大减少了.这样的代码既有效率,又减少了出现错误的几率,其益处是可见的.下面举两个例子比较一下

1.使用一般的sql语句进行控件绑定,常规代码如下:

1//Createtheconnectionandsqltobeexecuted

2stringstrConnTxt="Server=(local);Database=Northwind;IntegratedSecurity=True;";

3stringstrSql="select*fromProductswherecategoryid=1"

4

5//Createandopentheconnectionobject

6SqlConnectionobjConn=newSqlConnection(strConnTxt);

7objConn.Open();

8

9//Createtheconnamdobject

10SqlCommandobjCmd=newSqlCommand(strSql,objConn);

11objCmd.CommandType=CommandType.Text;

12

13//databindthedatagridbycallingtheExecuteReader()method

14DataGrid1.DataSource=objCmd.ExecuteReader();

15DataGrid1.DataBind();

16

17//closetheconnection

18objConn.Close();如果用微软封装的DataAccessApplicationBlock,其主要是sqlHelper类,代码如下:

1//Createtheconnectionstringandsqltobeexecuted

2stringstrSql="select*fromproductswherecategoryid=1";

3stringstrConnTxt="Server=(local);Database=Northwind;IntegratedSecurity=True;";

4

5DataGrid1.DataSource=SqlHelper.ExecuteReader(strConnTxt,CommandType.Text,strSql);

6DataGrid1.DataBind();

2.调用存储过程进行控件绑定

常规代码如下:

1//OpenaconnectiontoNorthwind

2SqlConnectionobjConn=newSqlConnection("Server=(local);Database=Northwind;IntegratedSecurity=True;");

3ObjConn.Open();

4

5//Createthestoredprocedurecommandobject

6SqlCommandobjCmd=newSqlCommand("getProductsCategory",objConn);

7objCmd.CommandType=CommandType.StoredProcedure;

8

9//createtheparameterobjectforthestoredprocedureparameter

10objCmd.Parameter.Add("@CategoryID",SqlDbType.Int);

11objCmd.Parameter["@CategoryID"].Value=1;

12

13//createourDataAdapterandDataSetobjects

14SqlDataAdapterobjDA=newSqlDataAdapter(objCmd);

15DataSetobjDS=newDataSet("Category_Results");

16

17//fillthedataset

18objDA.Fill(objDS);

19

20//databindthedatagrid

21DataGrid1.DataSource=objDS;

22DataGrid1.DataBind();

23

24//closeconnection

25objConn.Close();如果用微软封装的DataAccessApplicationBlock,其主要是sqlHelper类,代码如下:

1stringstrConn="Server=(local);Database=Northwind;IntegratedSecurity=True;";

2DataSetobjDS=SqlHelper.ExecuteDataset(strConn,CommandType.StoredProcedure,"getProductsByCategory",newSqlParameter("@CategoryID",1));

3

4DataGrid1.DataSource=objDS;

5DataGrid1.DataBind();

DataAccessApplicationBlock,有其封装的源代码和帮助文件,我们也可以根据项目需求做一下改动再编译成dll引入项目,以给项目开发带来便利.下载地址如下:

http://download.microsoft.com/download/VisualStudioNET/daabref/RTM/NT5/EN-US/DataAccessApplicationBlock.msi