Question

In my asp.net application I have added the connection string in each page Page_Load function and declared the string as public in top of the page.

I know this is wrong thing. The whole application is running the same connection, so I want to declare the connection string in only one place. Where should I declare the connection string? How can I access the connection string in each Connection?

public string connstring = "";

protected void Page_Load(object sender, EventArgs e)
{
    if (IsPostBack != true)
    {
        connstring = ConfigurationManager.ConnectionStrings["connString"].ToString();
        MySqlConnection connection = new MySqlConnection(connstring);
        // ----
    }
}

Answer 1

You already have defined the connection string in web.config, you don’t need to define it again in each page, just use the connection string from ConfigurationManager instead of creating a new string variable on each page.

ConfigurationManager.ConnectionStrings["connString"].ToString()

its better if you check for null prior to using the connection string.

if(ConfigurationManager.ConnectionStrings.Count > 0 && 
ConfigurationManager.ConnectionStrings["connString"] != null)