ASP.NET 4学习笔记(1) SQL注入攻击及解决方案.

 一, 定义:所谓SQL注入攻击是应用程序开发人员未预期地把SQL代码传入到应用程序的过程,只有那些直接使用用户提供的值构造SQL语句的应用程序才会受影响.

　　例如原SQL代码为:

　　select Orders.CustomerID,Orders.OrderID,Count(UnitPrice) as Items,SUM(UnitPrice*Quantity) as Total from Orders INNER JOIN [Order Details]on Orders.OrderID=[Order Details].OrderID where Orders.CustomerID='"+txtId.Text+"' GROUP BY Orders.OrderID,Orders.CustomerID

　　如果在txtId.Text所在的文本框中输入字符串:ALFKI' or '1'='1将会返回所有的订单记录,即便那些订单不是由ALFKI创建的,因为对每一行而言,1=1总是为true.

解决方案:采用参数化命令:

　　如使用参数化命令重写前面的代码为:

 protected void btnQuery_Click(object sender, EventArgs e)
        {
            string conStr = WebConfigurationManager.ConnectionStrings["Northwind"].ConnectionString;
            SqlConnection con = new SqlConnection(conStr);
            con.Open();
            string strSql = "select Orders.CustomerID,Orders.OrderID,Count(UnitPrice) as Items,SUM(UnitPrice*Quantity) as Total from Orders INNER JOIN [Order Details]on Orders.OrderID=[Order Details].OrderID where Orders.CustomerID=@CustomerID GROUP BY Orders.OrderID,Orders.CustomerID";
            SqlCommand cmd = new SqlCommand(strSql, con);
            cmd.Parameters.AddWithValue("@CustomerID", txtId.Text.Trim().ToString());
            SqlDataReader reader = cmd.ExecuteReader();
            GridView1.DataSource = reader;
            GridView1.DataBind();
            reader.Close();
            con.Close();
        }

　　这样就可以避免SQL注入攻击.