When 'login' button is clicked I would like to iterate through a column in a table and check if a match occurs. How would I go about doing this? I have connected through to a database and I'm reading from database and writing to database fine. I am not sure how I would iterate through a database.

P.S I'm new to both c# and visual studios. I am not having much trouble with C#, since I come over from Java however I'm struggling to get into grips with Visual studios.

• c#
• database
• visual-studio

This is simple you'll see.

            SqlConnection myConnection = new SqlConnection(@"Server = (Local); Integrated Security = True;" + "Database = insertDataBaseName"); // Assuming (Local)
            myConnection.Open();
            SqlCommand myCommand = myConnection.CreateCommand();
            myCommand.CommandText = ("SELECT UserName, Password,from Login"); // Where Login is your table . UserName and Password Columns
            SqlDataReader myReader = myCommand.ExecuteReader();
            bool login = false;

            while (myReader.Read())
            {
                if (userNameBox.Text.CompareTo(myReader["UserName"].ToString()) == 0 && passwordBox.Text.CompareTo(myReader["Password"].ToString()) == 0) // A little messy but does the job to compare your infos assuming your using a textbox for username and password
                {
                    login = true;
                }
            }

            if (login)
            {
                      //Your're in.
            }

            else
            {
                MessageBox.Show("Invalid UserName or Password", "Access Denied"); // Error message
            }

                 myReader.Close(); 
                 myConnection.Close(); // Just close everything

Hope this helps. Dont hesitate if you have any question on this code part.

in sql something like this will help

Select top(1) from Users where Id = @Id

or in linq

var user = (from u in users 
            where u.Id == id
            select u).SingleOrDefault();

If you are chekcing for a username password validation, I think you should not get all user records and loop Iterate thru that. What if you get 100000 user registrations ? You really want to iterate 100000 times ? Really ?

You should probably query for the purticular record you are looking for

Some thing like this

SELECT TOP 1 UserID,FIRSTNAME,LASTNAME,HASHED_PASSWORD,SALT WHERE USERNAME='kristy'

Execute that query againinst your database and see whether you have any records exist, If you have one record present, now you can validate the password with the data you have.