asp.net 使用using代碼塊 摘

"ado.net 2.0 技術內幕

強烈建議在Using代碼塊內所有可能的位置建立短期生存對象。

Using 塊確保及時在Using塊內波發生未處理異常時, 也會在該代碼塊的末尾調用 Dispose 方法。

 

例子:

string strConn, strSQL;
strconn = @"Data Source=.\SQLExpress;" + "Initial Catalog = Northwind;Integrated Security=True;";
strSQL = "SELECT CustomerID, CompanyName FROM Customers";
Using (SqlConnection cn = new SqlConnection(strConn)) {
    Try {
    cn.Open();
    }
    Catch (SqlException ex) {
        Consolse.WriteLine("Connect attempt failed");
        Consolse.WriteLine(" {0}", ex.Message);
return;
    }

    Using (SqlCommand cmd = new SqlCommand(strSQL, cn) {
try {
using (SqlDataReader rdr = cmd.ExecuteReader()) {
while (rdr.Read())
                Console.WriteLine(rdr[ "CompanyName"]);
                rdr.Close();
            }
        }
catch (SqlException ex) {
            Console.WriteLine("Query failed");
            Console.WriteLine("{0}", ex.Message);
return;
        }
    }
    cn.Close();
}

"