使用LINQ向数据库添加新元素 [英] Using LINQ to add new elements to a database

问题描述

大家好，

当我尝试使用LINQ在数据库中插入数据时，我收到了NullReferenceException.下面是按钮事件处理程序的代码，其中我正在向数据库中添加新项目.

Hello All,

When I am trying to use LINQ to insert data in a Database, I am getting a NullReferenceException. Below is the code for the Button Event Handler where I am adding new items to the Database.

protected void Button1_Click(object sender, EventArgs e)
    {
        string connectionString =ConfigurationManager.ConnectionStrings["DatabaseConnectionStrings"].ToString(); 
        MyClassesDataContext context = new MyClassesDataContext(connectionString);

        test t = new test();
        t.fname = TextBox1.Text;
        t.lname = TextBox2.Text;

        
        context.tests.InsertOnSubmit(t);
        context.SubmitChanges();
        ListBox1.DataBind();



    }

当我按下按钮时，它指向"string connectionString = ConfigurationManager.ConnectionStrings [" DatabaseConnectionStrings].ToString();" 说明使用"new"关键字创建对象实例"



我想connectionString的声明中有错误，但是我无法弄清楚.

非常感谢.

When i press the Button, it points to "string connectionString =ConfigurationManager.ConnectionStrings["DatabaseConnectionStrings"].ToString();" stating that "Use the "new" keyword to create an object instance"



I guess there is an error in the declaration of the connectionString, but I am unable to figure it out.

Many Thanks in Advance.

推荐答案

可以尝试，

Can you try,

string connectionString =  ConfigurationManager.ConnectionStrings["DatabaseConnectionStrings"].ConnectionString

并检查配置文件中的连接字符串.

and also check the connection string in config file.

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