When we work on ADO.NET you need to be sure about why SqlCommand is used.

Those things were, their are two kind of operations related to database:

First one are those which will make changes in the database

•  Insert
• Update
• Delete

And second one are is which will not make any change to the database

• Select

SqlCommand is used for the first one when we have insert update or delete operation to perform in the database.

For this we always have to open the connection to make changes to the database.

And after finishing work connection should be closed.

 SqlCommand cmd = new SqlCommand("uspRegisterUser", sqlConnection);

  cmd.CommandType = CommandType.StoredProcedure;

  cmd.Parameters.Add("@FirstName", SqlDbType.VarChar, 50).Value = empobj.FirstName;

  cmd.Parameters.Add("@LastName", SqlDbType.VarChar, 50).Value = empobj.LastName;

  cmd.Parameters.Add("@ProfileImage", SqlDbType.VarChar, 500).Value = ConfigurationManager.AppSettings["ProfileImageBaseAddress"].ToString();

 result = Convert.ToInt32(cmd.ExecuteNonQuery());
            

I have used it with the stored procedure name uspRegisterUser that takes first name last name and profile image as argument.