Ошибка в коде, С#

Question

ошибка в коде, C# visual studio 2019

Ошибка	CS0119	&#34;ConnectionString&#34; является тип, который недопустим в данном контексте.

using MongoDB.Driver.Core.Configuration; 
using System; 
using System.Collections.Generic; 
using System.ComponentModel; 
using System.Data; 
using System.Data.SqlClient; 
using System.Drawing; 
using System.Linq; 
using System.Text; 
using System.Threading.Tasks; 
using  System.Windows .Forms; 
 
namespace WindowsFormsApp4 
{ 
    public partial class Form1 : Form 
    { 
        public Form1() 
        { 
            InitializeComponent(); 
            string login = textBox1.Text; 
            string password = textBox2.Text; 
            string role = Check(login, password); 
                if (role == &#34;Admin&#34;) 
                    MessageBox.Show(&#34;Admin&#34;); 
                else if (role == &#34;Master&#34;) 
                    MessageBox.Show(&#34;Master&#34;); 
                else if(role == &#34;User&#34;) 
                    MessageBox.Show(&#34;User&#34;); 
                else if (role == &#34;Nothing&#34;) 
                    MessageBox.Show(&#34;Nothing&#34;); 
        } 
        private string Check(string login, string password) 
        { 
            SqlConnection connection = new SqlConnection(ConnectionString); 
            string query = &#34;SELECT role FROM {Table} WHERE (login = @login AND password)&#34;; 
            SqlCommand cmd = new SqlCommand(query, connection); 
             connection.Open (); 
            cmd.Parameters.AddWithValue(&#34;login&#34;, login); 
            cmd.Parameters.AddWithValue(&#34;password&#34;, password); 
            SqlDataReader reader = cmd.ExecuteReader(); 
            if ( reader.Read ()) 
            { 
                return reader[&#34;role&#34;].ToString(); 
            } 
            else return null; 
        } 
    } 
}

Как исправить ошибку?

робот д24 · Answer

Надо создать переменную ConnectionString и в неё вписать данные для подключения

Татьяна · Answer

using System; 
using System.Data.SqlClient; 
using System.Windows.Forms; 
 
namespace WindowsFormsApp4 
{ 
    public partial class Form1 : Form 
    { 
        private const string ConnectionString = "Your_Connection_String_Here"; 
 
        public Form1() 
        { 
            InitializeComponent(); 
        } 
 
        private void AuthenticateButton_Click(object sender, EventArgs e) 
        { 
            string login = textBox1.Text; 
            string password = textBox2.Text; 
            string role = CheckCredentials(login, password); 
            MessageBox.Show(role ?? "Неверные учетные данные"); 
        } 
 
        private string CheckCredentials(string login, string password) 
        { 
            const string query = "SELECT role FROM Users WHERE login = @login AND password = @password"; 
 
            using (var connection = new SqlConnection(ConnectionString)) 
            using (var cmd = new SqlCommand(query, connection)) 
            { 
                cmd.Parameters.AddWithValue("@login", login); 
                cmd.Parameters.AddWithValue("@password", password); 
 
                connection.Open(); 
                return (string)cmd.ExecuteScalar(); 
            } 
        } 
    } 
}