sql - Execute query using C# -

i trying execute sql code, connected directly database, don't know how execute query.

sqlconnection connect = new sqlconnection("database"); sqlconnection myconnection = connect; connect.open(); sqldataadapter adptador = new sqldataadapter(@"query", connect); datatable tabela = new datatable(); adptador.fill(table); clientcontext.web.lists.getbytitle("title"); clientcontext.executequery(); list list = clientcontext.web.lists.getbytitle("listname"); clientcontext.load(list); listitemcreationinformation listitemcreationinformation = new listitemcreationinformation(); listitem item = list.additem(listitemcreationinformation);  foreach (datarow row in tabela.rows) {     item["lastmodifiedby"] = row["lastmodifiedby"].tostring();     item.update();     cm = new sqlcommand("sql command");     **execute cm**     clientcontext.executequery(); } 

sqlcommand has executereader, executing command , returning dataset, executescalar returning single value of primitive type (int, string, etc.), or executenonquery returning nothing. can pass command sqldataadapter, , use populate datatable object.

please google sqlcommand , find lots of examples.