Question

我一直在尝试通过App.config中的连接字符串连接到我的MS Sql数据库，但由于某种原因它无法登录，我似乎无法弄明白。

这是我的Connection方法：

public void Con()
{

        string userName = userNameBox.Text;
        string passWord = passWordBox.Text;

        bool loginFail;

        SqlConnection Conn = new SqlConnection(ConfigurationManager.ConnectionStrings["lagerConn"].ConnectionString);

        //Search Connstring for User ID= & Password= and replace with username and password from Textboxes
        if (_Connstring.Contains("User ID="))
        {
            _Connstring = _Connstring.Replace("User ID=;", "User ID=" + userName + ";");

        }
        if (_Connstring.Contains("Password="))
        {
            _Connstring = _Connstring.Replace("Password=", "Password='" + passWord + "'");
        }

        try
        {
            Conn.Open();
            Conn.Close();
            loginFail = false;
        }catch
        {
            MessageBox.Show("Login Failed");
            loginFail = true;
        }
        if(loginFail == false) //If login is successful it will change to the next form and hide the Connect form
        {
            mainMenu secondForm = new mainMenu();
            secondForm.Show();
            this.Hide();

        }

    }`

这是我的App.config

        <add name="lagerConn" connectionString="Data Source=LagerServer;Initial Catalog=LagerDB;Persist Security Info=True;User ID=;Password="
        providerName="System.Data.SqlClient" />
</connectionStrings>

I got this exception

Answer 1

根本没有必要在连接字符串中放置一个空的用户ID和密码字段。完全抛弃它们，摆脱那无意义的Persist Security Info。使用连接字符串构建器，例如

SqlConnection builder = new SqlConnectionStringBuilder(ConfigurationManager.ConnectionStrings["lagerConn"].ConnectionString);

builder.UserID = userID;
builder.Password = password;

SqlConnection connection = new SqlConnection(builder.ConnectionString);

之后，不要只提供一般性错误消息并忽略系统提供给您的信息。看一下例外，它会告诉你出了什么问题。

Answer 2

尝试：

string userName = userNameBox.Text;
string passWord = passWordBox.Text;
string connStr = ConfigurationManager.ConnectionStrings["lagerConn"].ConnectionString;
connStr = connStr.Replace("User ID=;", "User ID=" + userName + ";");
connStr = connStr.Replace("Password=", "Password='" + passWord + "'");
bool loginFail = false;
try{
    using (SqlConnection Conn = new SqlConnection(connStr){
       loginFail true;
    }
}
catch (SqlConnection sqlEx){
   //already false
}

是的，谨防sql注入攻击！

Answer 3

首先，你不应该在TextBox中编写UserID和Password，在连接字符串中将它们写为静态。例外告诉你一切 - ＆gt;用户''登录失败。您没有在文本框中写入正确的用户名或密码。

无法连接到数据库C＃

3 个答案: