using application role of sql server2005 express in multiple forms in c#

问题

I have a C# .net winforms application with two forms which connects to sql express using connection string.

form1 connects to sql with trusted connection. connection string is given in the app.config file.

now, a button on form1 is clicked which changes the connection to application role credentials.

now, form2 opens & it has a button which when clicked needs to create a database using the application role settings.

so how do i use the application role settings created in form1 into form2. because to execute the database creation query the Form2 needs a new connection object.

So, do i have to add another app.config file or what else?

------------------------EDITED----------------------------------------------------

public partial class Form1 : Form
{
    SqlConnection conn = new SqlConnection();

    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
             //new code for using conenction string from app.config file added 
                //  Read appSettings
                    string title = ConfigurationSettings.AppSettings["ApplicationTitle"];
                    string connectString =
                    ConfigurationSettings.AppSettings["ConnectionString"];
                    conn.ConnectionString = connectString;
           //new code ends

        conn.Open();
        string setapprole = "sp_setapprole 'my_app' , 'app_pass' ";
        SqlCommand cmd_app = new SqlCommand(setapprole, conn);
        SqlDataReader approle_reader = cmd_app.ExecuteReader();
        approle_reader.Close();

        Form2 f2 = new Form2();
        f2.Show();
    }

}

--------------------------------FORM2.CS------------------------------

public partial class Form2 : Form
{
   //how to connect to the database, 
    public Form2()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {  
        string query = "create database new_db";
         //I WANT TO USE the conn object here, 
          //& want the connection to use the application role
         // which was set in Form1.cs 
        SqlCommand cmd = new SqlCommand(query, conn); 
        SqlDataReader createdb = cmd.ExecuteReader();

    }
}

---------------EDITED-1----------------------------------

my app.config file :

`xml version="1.0" encoding="utf-8"

configuration

appSettings add key="ApplicationTitle" value="Setup Database , Tables and Permissions" add key="ConnectionString" value="Server=localhost; Trusted_Connection=true" appSettings

configuration

回答1:

Use a SqlConnectionStringBuilder to modify the connection parameters and then open a new connection to the DB.

EDIT

public partial class Form1 : Form
    {
        SqlConnection conn = new SqlConnection("Data Source=TODO;Initial Catalog=TODO;Integrated Security=True");

        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            using (SqlCommand command = new SqlCommand("sp_setapprole 'my_app' , 'app_pass' ", conn))
            {
                command.CommandType = CommandType.Text;
                conn.Open();
                command.ExecuteNonQuery();
            }
            // The application role is set and remains active until the user disconnects

            Form2 f2 = new Form2(conn);
            f2.Show();
        }
    }

    public partial class Form2 : Form
    {
        SqlConnection conn = null;
        //how to connect to the database, 
        public Form2(SqlConnection conn)
        {
            InitializeComponent();
            this.conn = conn;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            try
            {
                using (SqlCommand command = new SqlCommand("create database new_db", conn))
                {
                    command.CommandType = CommandType.Text;
                    command.ExecuteNonQuery();
                }
            }
            finally
            {
                // Important to close the DB connection (at which point the approle becomes inactive)
                conn.Close();
            }

        }
    }

来源：https://stackoverflow.com/questions/5114558/using-application-role-of-sql-server2005-express-in-multiple-forms-in-c-sharp