Sql Connection in Windows Form

Ramco Ramco

I have created below Class. I want connection should be called once for all forms. I am using Windows Form Application

class DBConnection
    {
        public SqlConnection con;
        public void Connection()
        {
            con = new SqlConnection("Data Source = .;Initial Catalog = Pl_Live; Integrated Security=true;");
        }
    }

Thanks

2 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vijay Pratap Singh2y ago

Accepted answer

Hello Ramco,
it seems like you're missing a constructor to initialize the connection.

using System.Data.SqlClient;

class DBConnection
{
    public SqlConnection con;

    // Constructor to initialize the connection
    public DBConnection()
    {
        con = new SqlConnection("Data Source = .;Initial Catalog = Pl_Live; Integrated Security=true;");
    }

    // Method to open the connection
    public void OpenConnection()
    {
        if (con.State != System.Data.ConnectionState.Open)
        {
            con.Open();
        }
    }

    // Method to close the connection
    public void CloseConnection()
    {
        if (con.State != System.Data.ConnectionState.Closed)
        {
            con.Close();
        }
    }
}

With this modified class, you can now create an instance of DBConnection and call the OpenConnection() method whenever you need to use the connection.

using System;
using System.Windows.Forms;

namespace YourNamespace
{
    public partial class YourForm : Form
    {
        private DBConnection dbConnection;

        public YourForm()
        {
            InitializeComponent();

            // Initialize the database connection
            dbConnection = new DBConnection();
            dbConnection.OpenConnection(); // Open the connection
        }

        // Make sure to close the connection when the form is closed
        protected override void OnFormClosed(FormClosedEventArgs e)
        {
            base.OnFormClosed(e);

            // Close the connection
            dbConnection.CloseConnection();
        }

        // Now you can use dbConnection.con to access the SqlConnection object
        // and perform your database operations.
    }
}

Hope this will help.
Thanks

Ashutosh Singh2y ago
To ensure that the database connection is established once for all forms in your Windows Forms application, you can use a singleton pattern for your DBConnection class. This pattern ensures that only one instance of the class is created and shared across all forms. Here's how you can modify your class:
```
using System.Data.SqlClient;

class DBConnection
{
    private static readonly Lazy instance = new Lazy(() => new DBConnection());

    public static DBConnection Instance => instance.Value;

    public SqlConnection Connection { get; }

    private DBConnection()
    {
        Connection = new SqlConnection("Data Source = .;Initial Catalog = Pl_Live; Integrated Security=true;");
    }
}
```
With this setup:
- The DBConnection class has a private constructor to prevent direct instantiation.
- A static Instance property is provided to access the single instance of the class.
- The Connection property provides access to the SqlConnection instance.
- The Connection is initialized only once when the class is first accessed.
Now, you can use DBConnection.Instance.Connection to access the shared connection instance across all forms in your application. For example:
```
using System.Windows.Forms;

public class YourForm : Form
{
    public YourForm()
    {
        InitializeComponent();
        // Access the shared database connection instance
        SqlConnection connection = DBConnection.Instance.Connection;
        // Use the connection as needed
    }
}
```
This way, you ensure that there's only one database connection instance shared across all forms, and it's initialized only once when first accessed.