檢查數據庫的用戶名或密碼OledDb Connection

Question

我正在嘗試檢查一個數據庫，我已連接到我的程序的用戶名和密碼，我有我的查詢，但我將如何檢查它對表。

    private void button1_Click(object sender, EventArgs e)
    {
        Menu m1 = new Menu();
        string connectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=UserAccounts.accdb; Persist Security Info=False;";
        OleDbCommand cmd = new OleDbCommand("Select * from UserAccounts where Username = " +userBox.Text + " and Password] = " + Password.Text + "");
        using (OleDbConnection conn = new OleDbConnection(connectionString))
        {
            try
            {
                conn.Open();
                this.Hide();
                m1.Show();
            }
            catch (Exception exc)
            {
                MessageBox.Show(exc.Message);
            }
        }
    }

Answer 1

你已經非常接近了，讓我們稍微修改一下：

private void button1_Click(object sender, EventArgs e)
{
    Menu m1 = new Menu();
    string connectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=UserAccounts.accdb; Persist Security Info=False;";
    using (OleDbConnection conn = new OleDbConnection(connectionString))
    {
        try
        {
            conn.Open();
            using (OleDbCommand cmd = new OleDbCommand("Select * from UserAccounts where Username = @Username and Password = @Password"))
            {
                cmd.Parameters.AddWithValue("@Username", userBox.Text);
                cmd.Parameters.AddWithValue("@Password", Password.Text);

                using (OleDbDataReader r = cmd.ExecuteReader())
                {
                    if (r.HasRows)
                    {
                        // do something here
                    }
                }
            }
            this.Hide();
            m1.Show();
        }
        catch (Exception exc)
        {
            MessageBox.Show(exc.Message);
        }
    }
}

Answer 2

如果您只是想檢查用戶名和密碼是否存在，您可以這樣做

public bool IsValid(string username, string password)
        {
            string connectionString = @"...connectionstring";


            string SQL = "SELECT * FROM UserAccounts where [Username]='" + username + "' and [Password]='" + password + "'";

            OdbcConnection conn = new OdbcConnection(connectionString);

            OdbcCommand cmd = new OdbcCommand(SQL);
            cmd.Connection = conn;

            conn.Open();

            OdbcDataReader reader = cmd.ExecuteReader();

            if (reader.HasRows)
            {
                return true;
            }

            return false;
        }