Sharepoint - Field manipulation in sharepoint list programmatically

Add column to sharepoint list

using (SPSite siteCollection = new SPSite(url))

            {

                using (SPWeb web = siteCollection.OpenWeb())

                {

                     SPList list = web.Lists[“ListName”];

                      list.Fields.Add("fieldName", SPFieldType.Boolean, true);

                     list.Update();

   

                    }

                }

Delete column from list

using (SPSite siteCollection = new SPSite(url))

            {

                using (SPWeb web = siteCollection.OpenWeb())

                {

                     SPList list = web.Lists[“ListName”];

                      list.Fields[“fieldname”].Delete();

                     list.Update();

   

                    }

                }

Add column from site column list

using (SPSite siteCollection = new SPSite(url))

            {

                using (SPWeb web = siteCollection.OpenWeb())

                {

                     SPList list = web.Lists[“ListName”];

                      list.Fields.Add(siteCollection.RootWeb.Fields[fieldName]);

                                    list.Update();

   

                    }

                }