Best practice ms sql server connection in large C# or vb.net application

Whatever may be the architecture, disposing objects, when it is no longer required will be the best practice.

Benefits
-> It helps to improve your Execution Time.
-> As you are disposing the object, so it can give that connection to other application.

Note
As you might know the DataBases have limited number of connections.
So, if you will open and dispose after a long time without any need, then that will just increase the number.
After a certain number of connections, DataBase will not connect even if you create connections.

It is best practice to close the connection when ever data retrieval has completed.

=>data base has limited connections it gives the connections to others if u close that.
=>if the connection is in open state and you are try to open it again in your application
it throws an error
=> and if you are not intreasting in closing the connection every time you open,just wrap the
data base code in side using,it will take care of closing the connection automatically
when scope is lost.
=>its a good practice to open the connection as late as possible and close it as early as possible

Quote:

Most "best practices" tell us to open connections as late as possible (right before executing any SQL) and closing them as soon as possible (right after the last bit of data has been extracted.

using (SqlConnection conn = new SqlConnection(...))
{
    using(SqlCommand cmd = new SqlCommand(..., conn))
    {
        conn.Open();
        using(DataReader dr = cmd.ExecuteReader())  // or load a DataTable, ExecuteScalar, etc.
        {
             ...
        {
    }
}

From:
C# Data Connections Best Practice[^]