无效的对象名称tabl_login

Question

所以它在表格中我在线搜索但没有任何帮助。 这是代码。我不明白它为什么现在给我错误，而不是之前。

我正在使用Visual Studio 2015 btw。

public partial class loginpage : Form
{
    public loginpage()
    {
            InitializeComponent();
    }

    // Connection String
    string cs = @"Data Source=MS-LAPTOP\SQLEXPRESS;Integrated Security=True;Connect Timeout=15;Encrypt=False;TrustServerCertificate=True;ApplicationIntent=ReadWrite;MultiSubnetFailover=False";
    //btn_Submit Click event

    public sealed class SecurePasswordHasher
    {
        /// <summary>
        /// Size of salt
        /// </summary>
        private const int SaltSize = 16;

        /// <summary>
        /// Size of hash
        /// </summary>
        private const int HashSize = 20;

        /// <summary>
        /// Creates a hash from a password
        /// </summary>
        /// <param name="password">the password</param>
        /// <param name="iterations">number of iterations</param>
        /// <returns>the hash</returns>
        public static string Hash(string password, int iterations)
        {
                //create salt
                byte[] salt;
                new RNGCryptoServiceProvider().GetBytes(salt = new byte[SaltSize]);

                //create hash
                var pbkdf2 = new Rfc2898DeriveBytes(password, salt, iterations);
                var hash = pbkdf2.GetBytes(HashSize);

                //combine salt and hash
                var hashBytes = new byte[SaltSize + HashSize];
                Array.Copy(salt, 0, hashBytes, 0, SaltSize);
                Array.Copy(hash, 0, hashBytes, SaltSize, HashSize);

                //convert to base64
                var base64Hash = Convert.ToBase64String(hashBytes);

                //format hash with extra information
                return string.Format("$MYHASH$V1${0}${1}", iterations, base64Hash);
        }

        /// <summary>
        /// Creates a hash from a password with 10000 iterations
        /// </summary>
        /// <param name="password">the password</param>
        /// <returns>the hash</returns>
        public static string Hash(string password)
        {
                return Hash(password, 10000);
        }

        /// <summary>
        /// Check if hash is supported
        /// </summary>
        /// <param name="hashString">the hash</param>
        /// <returns>is supported?</returns>
        public static bool IsHashSupported(string hashString)
        {
                return hashString.Contains("$MYHASH$V1$");
        }

        /// <summary>
        /// verify a password against a hash
        /// </summary>
        /// <param name="password">the password</param>
        /// <param name="hashedPassword">the hash</param>
        /// <returns>could be verified?</returns>
        public static bool Verify(string password, string hashedPassword)
        {
                //check hash
                if (!IsHashSupported(hashedPassword))
                {
                    throw new NotSupportedException("The hashtype is not supported");
                }

                //extract iteration and Base64 string
                var splittedHashString = hashedPassword.Replace("$MYHASH$V1$", "").Split('$');
                var iterations = int.Parse(splittedHashString[0]);
                var base64Hash = splittedHashString[1];

                //get hashbytes
                var hashBytes = Convert.FromBase64String(base64Hash);

                //get salt
                var salt = new byte[SaltSize];
                Array.Copy(hashBytes, 0, salt, 0, SaltSize);

                //create hash with given salt
                var pbkdf2 = new Rfc2898DeriveBytes(password, salt, iterations);
                byte[] hash = pbkdf2.GetBytes(HashSize);

                //get result
                for (var i = 0; i < HashSize; i++)
                {
                    if (hashBytes[i + SaltSize] != hash[i])
                    {
                        return false;
                    }
                }
                return true;
            }
}

private void button2_Click(object sender, EventArgs e)
{
    //Hash
    var hash = SecurePasswordHasher.Hash("password");

    //Verify
    var result = SecurePasswordHasher.Verify("password", hash);

    if (txtUsername.Text == "" || txt_Password.Text == "")
    {
        MessageBox.Show("Please provide a Username and Password");
        return;
    }

    try
    {
        //Create SqlConnection
        SqlConnection con = new SqlConnection(cs);

        SqlCommand cmd = new SqlCommand("Select * from tabl_login where UserName=@username and Password=@password", con);
        cmd.Parameters.AddWithValue("@username", txtUsername.Text);
        cmd.Parameters.AddWithValue("@password", txt_Password.Text);

        con.Open();

        SqlDataAdapter adapt = new SqlDataAdapter(cmd);
        DataSet ds = new DataSet();
        adapt.Fill(ds);

        con.Close();

        int count = ds.Tables[0].Rows.Count;

        //If count is equal to 1, than show frmMain form
        if (count == 1)
        {
            MessageBox.Show("Login Successful!");

            Form1 objFrmMain = new Form1();
            this.Hide();
            objFrmMain.ShowDialog();
            this.Close();
        }
        else
        {
            MessageBox.Show("Login Failed!");
        }
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.Message);
    }
}

此处还有截图

Answer 1

您的连接不正确。它错过了数据库名称。

    // Connection String
    string cs = @"Data Source=MS-LAPTOP\SQLEXPRESS;Integrated Security=True;Connect Timeout=15;Encrypt=False;TrustServerCertificate=True;ApplicationIntent=ReadWrite;MultiSubnetFailover=False";
   

将其更改为

 // Connection String
    string cs = @"Data Source=MS-LAPTOP\SQLEXPRESS;Integrated Security=True;Initial Catalog=DataBaseName;Connect Timeout=15;Encrypt=False;TrustServerCertificate=True;ApplicationIntent=ReadWrite;MultiSubnetFailover=False";
  

Answer 2

你希望它是

[数据库名称]。[模式]。[表名]

而不是 tabl_login