无法连接到SQL数据库-用户名和密码丢失

Question

having difficulty with a bit of code I have. I think variables are stuck inside the method I'm invoking and when I go to run that method again variables are no longer there.

Below is an example of my main:

        public partial class Login : Form
{

    public Login()
    {
        InitializeComponent();
    }
    sqlconnect sql = new sqlconnect();
    public string pass;
    public string user;


    public void button1_Click(object sender, EventArgs e)
    {
        //Username and password textboxes send to public strings
        user = textBox1.Text;
        pass = textBox2.Text;

            try
            {
                //try connecting to SQL database using SQL class
                sql.GetSqlConnection();
                sql.myConnection.Open();
                this.Hide();

            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

Here is the SQL connection class:

    namespace NHS_Workshop_System
         {

public class sqlconnect
{
    public SqlConnection myConnection { get; set; }
    Settings1 set = new Settings1();
    Login var = new Login();

    public SqlConnection GetSqlConnection()
    {
        if (myConnection == null)
            myConnection = new SqlConnection("user id="+(var.user)+"; password="+(var.pass)+";server="+(set.SelectServer)+";Trusted_Connection="+(set.SelectContype)+";database="+(set.SelectDataBase)+"; connection timeout="+(set.Condrop)+"");

        return myConnection;
    }


}

}

So when I try to login it may work first time but if another form tries to run that method the username and password are missing. I'm not sure how to make the variables global so that every time I run the method it calls those details without fail. So the second time it uses sqlconnection on another form the ex message states that username and password are non existent. Is this a scoping issue if so can someone shed some light on how i might go about this maybe a new method of gaining access to an SQL server? Thank you tearing out my hair

Answer 1

Below is the answer for your question the way you have it now. But I strongly recommend you to think about what you are doing since your class logics doesn't seem to be very good. I see that your trying to implement Singleton which is good, but you can still make more instances of sqlconnect if you would like.

---

In your Login class, pass this instance of Login so the sqlconnector knows the user and pass that is declared here.

public partial class Login : Form
{

// Old style - sqlconnect sql = new sqlconnect();
sqlconnect sql;
public string pass; // These arent declared and wont be of use for your sql connect class
public string user;

public Login( String pass, String user )
{
    this.pass = pass;
    this.user = user;
    // Now that we have a login with declared variables, pass it to the sqlconnect object
    this.sql = new sqlconnect(this);
    InitializeComponent();
}

Now in your sqlconnect class, before your Login variable was just empty. Now you have received an instance of it in your constructor that has it's variables set,

public class sqlconnect
{
    public SqlConnection myConnection { get; set; }
    Settings1 set = new Settings1();
    // Here you maked a new one, use the existing instead from which this class is called.
    // changed variable named from var to login..
    Login login; 


    // *NEW* Constructor where you pass your login object
    public sqlconnect(Login login)
    {
        this.login = login;
    }

    public SqlConnection GetSqlConnection()
    {
        if (myConnection == null)
            myConnection = new SqlConnection("user id="+(login.user)+"; password="+(login.pass)+";server="+(set.SelectServer)+";Trusted_Connection="+(set.SelectContype)+";database="+(set.SelectDataBase)+"; connection timeout="+(set.Condrop)+"");

        return myConnection;
    }


}