為了方便的訪問數據,微軟自己封裝了一個數據訪問模塊, 即Data Access Application Block. 通過它,我們用來訪問數據庫的編碼量大大減少了. 這樣的代碼既有效率,又減少了出現錯誤的幾率,其益處是可見的. 下面舉兩個例子比較一下
1. 使用一般的sql語句進行控件綁定, 常規代碼如下:
1//Create the connection and sql to be executed
2string strConnTxt = "Server=(local);Database=Northwind;Integrated Security=True;";
3string strSql = "select * from Products where categoryid = 1"
4
5//Create and open the connection object
6SqlConnection objConn = new SqlConnection(strConnTxt);
7objConn.Open();
8
9//Create the connamd object
10SqlCommand objCmd = new SqlCommand(strSql, objConn);
11objCmd.CommandType = CommandType.Text;
12
13//databind the datagrid by calling the ExecuteReader() method
14DataGrid1.DataSource = objCmd.ExecuteReader();
15DataGrid1.DataBind();
16
17//close the connection
18objConn.Close();如果用微軟封裝的Data Access Application Block, 其主要是sqlHelper類,代碼如下:
1//Create the connection string and sql to be executed
2string strSql = "select * from products where categoryid = 1";
3string strConnTxt = "Server=(local);Database=Northwind;Integrated Security=True;";
4
5DataGrid1.DataSource = SqlHelper.ExecuteReader(strConnTxt, CommandType.Text, strSql);
6DataGrid1.DataBind();
2. 調用存儲過程進行控件綁定
常規代碼如下:
1//Open a connection to Northwind
2SqlConnection objConn = new SqlConnection("Server=(local);Database=Northwind;Integrated Security=True;");
3ObjConn.Open();
4
5//Create the stored procedure command object
6SqlCommand objCmd = new SqlCommand("getProductsCategory", objConn);
7objCmd.CommandType = CommandType.StoredProcedure;
8
9//create the parameter object for the stored procedure parameter
10objCmd.Parameter.Add("@CategoryID", SqlDbType.Int);
11objCmd.Parameter["@CategoryID"].Value = 1;
12
13//create our DataAdapter and DataSet objects
14SqlDataAdapter objDA = new SqlDataAdapter(objCmd);
15DataSet objDS = new DataSet("Category_Results");
16
17//fill the dataset
18objDA.Fill(objDS);
19
20//databind the datagrid
21DataGrid1.DataSource = objDS;
22DataGrid1.DataBind();
23
24//close connection
25objConn.Close();如果用微軟封裝的Data Access Application Block,其主要是sqlHelper類,代碼如下:
1string strConn = "Server=(local);Database=Northwind;Integrated Security=True;";
2DataSet objDS = SqlHelper.ExecuteDataset(strConn, CommandType.StoredProcedure, "getProductsByCategory", new SqlParameter("@CategoryID", 1));
3
4DataGrid1.DataSource = objDS;
5DataGrid1.DataBind();
Data Access Application Block, 有其封裝的源代碼和幫助文件,我們也可以根據項目需求做一下改動再編譯成dll引入項目,以給項目開發帶來便利. 下載地址如下:
http://download.microsoft.com/download/VisualStudioNET/daabref/RTM/NT5/EN-US/DataAccessApplicationBlock.msi
