C#表单未将值插入SQL Server数据库 [英] C# Form not inserting values into SQL Server database

问题描述

我有一个简单的创建新用户表单，该表单从两个文本框(用户名和密码)中获取值. button2 click事件应采用这些值，并将它们插入数据库的用户"表中.但是，当我运行代码时，该消息框似乎显示已添加数据，因此我无法使用VS2010在数据库中查看数据.

I have a simple create a new user form which takes values from two text boxes, username and password. The button2 click event should take these values and insert them into the Users table in the database. However, when I run my code the message box appears to say the data has been added, I cannot see the data in the database using VS2010.

请参阅VS中的数据库连接的屏幕截图.我还在VS中创建了数据库的数据源.

See screen shot for the database connection in VS. I have also created a datasource of the database in VS.

有什么想法吗?

非常感谢.

private void button2_Click(object sender, EventArgs e)
    {
        string username = txtUsername.Text;
        string password = txtPassword.Text;
        string sqlquery;
        string connection = @"Data Source=.\SQLEXPRESS;AttachDbFilename='C:\Users\Nick\Documents\Visual Studio 2010\Projects\DebenhamsProjectOffice V.01\DebenhamsProjectOffice V.01\DebenhamsProjectOfficeDatabase.mdf';Integrated Security=True;Connect Timeout=30;User Instance=True";
        SqlConnection cn = new SqlConnection(connection);
        try
        {
            cn.Open();
        }
        catch (Exception)
        {
            MessageBox.Show("Unable to connect to Database");
        }

        sqlquery = "INSERT INTO Users (Username, Password) VALUES ('" + txtUsername.Text + "','" + txtPassword.Text + "')";
        try
        {
            SqlCommand command = new SqlCommand(sqlquery, cn);
            command.Parameters.AddWithValue("Username", username);
            command.Parameters.AddWithValue("Password", password);
            command.Parameters.Clear();
            MessageBox.Show("User Added");
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
        txtUsername.Text = "";
        txtPassword.Text = "";
        cn.Close();
    }

推荐答案

只需尝试代码修复.有些元素至关重要，有些则优雅. 尝试一下，它可能会起作用，或者可能会指出错误的位置:

Just trying a code fix. Some elements are crucial, some are just elegant. Try it, it might work., or could point to where the error is:

private void button2_Click(object sender, EventArgs e)
    {
        string username = txtUsername.Text;
        string password = txtPassword.Text;
        string sqlquery;

        //Put away the apostrophes and used twice double quotations for
        //the full path of the database file:
        string connection = @"Data Source=.\SQLEXPRESS;AttachDbFilename=""C:\Users\Nick\Documents\Visual Studio 2010\Projects\DebenhamsProjectOffice V.01\DebenhamsProjectOffice V.01\DebenhamsProjectOfficeDatabase.mdf"";Integrated Security=True;Connect Timeout=30;User Instance=True";
        SqlConnection cn = new SqlConnection(connection);

        /* Better to let the program fail than think it's open and moving on
        removed try, catch*/
        cn.Open();


        //Why using your TextBoxes values if you already created strings?
        //changed

        //you should also be careful users can't type something like "') in the      
        //textboxes or they may cause a SQL injection

        sqlquery = "INSERT INTO Users (Username, Password) VALUES ('" + username + "','" + password + "')";

        try
        {
            SqlCommand command = new SqlCommand(sqlquery, cn);
            /* unnecessary since you already built a query command.Parameters.AddWithValue("Username", username);
            command.Parameters.AddWithValue("Password", password);
            command.Parameters.Clear();   */

            //Missing!!
            command.ExecuteNonQuery();
            MessageBox.Show("User Added");
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }

        //Elegance
        txtUsername.Clear();
        txtPassword.Clear();
        cn.Close();
    }

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