ADO.NET对象的构造(7)_OleDbParameter(下)

n overloads public overridable function add(byval value as object) as integer implements ilist.addn overloads public function add(byval parametername as string,byval value as object) as oledbparametern overloads public function add(byval value as oledbparameter) as oledbparametern overloads public function add(byval parametername as string,byval oledbtype as oledbtype) as oledbparametern overloads public function add(byval parametername as string,byval oledbtype as oledbtype,byval size as integer) as oledbparametern overloads public function add(byval parametername as string,byval oledbtype as oledbtype,byval size as integer,byval sourcecolumn as string) as oledbparameter示例public sub createoledbparamcoll(myconn as oledbconnection) dim mycommand as oledbcommand = new oledbcommand("select * from customers where customerid = ?", myconn) dim myparamcollection as oledbparametercollection = mycommand.parameters dim myparm as object = new oledbparameter("customerid", oledbtype.varchar) dim pindex as integer = myparamcollection.add(myparm) dim myparm as oledbparameter = myparamcollection.add(new oledbparameter("customerid", oledbtype.varchar)) dim myparm as oledbparameter = myparamcollection.add("customerid", “customeridvalue”); dim myparm as oledbparameter = myparamcollection.add("customerid", oledbtype.varchar) dim myparm as oledbparameter = myparamcollection.add("customerid", oledbtype.varchar, 5) dim myparm as oledbparameter = myparamcollection.add("customerid", oledbtype.varchar, 5, "customerid")end sub 示例public shared function createcustomeradapter(conn as oledbconnection) as oledbdataadapter dim da as oledbdataadapter = new oledbdataadapter() dim cmd as oledbcommand dim parm as oledbparameter ' create the selectcommand. cmd = new oledbcommand("select * from customers where country = @country and city = @city", conn) cmd.parameters.add("@country", oledbtype.varchar, 15) cmd.parameters.add("@city", oledbtype.varchar, 15) da.selectcommand = cmd ' create the insertcommand. cmd = new oledbcommand("insert into customers (customerid, companyname) values (@customerid, @companyname)", conn) cmd.parameters.add("@customerid", oledbtype.char, 5, "customerid") cmd.parameters.add("@companyname", oledbtype.varchar, 40, "companyname") da.insertcommand = cmd ' create the deletecommand. cmd = new oledbcommand("delete from customers where customerid = @customerid", conn) parm = cmd.parameters.add("@customerid", oledbtype.char, 5, "customerid") parm.sourceversion = datarowversion.original da.deletecommand = cmd ' create the updatecommand. cmd = new oledbcommand("update customers set customerid = @customerid, companyname = @companyname where customerid = @oldcustomerid", conn) cmd.parameters.add("@customerid", oledbtype.char, 5, "customerid") cmd.parameters.add("@companyname", oledbtype.varchar, 40, "companyname") parm = cmd.parameters.add("@oldcustomerid", oledbtype.char, 5, "customerid") parm.sourceversion = datarowversion.original da.updatecommand = cmd return daend function以次两行parm = cmd.parameters.add("@customerid", oledbtype.char, 5, "customerid")parm.sourceversion = datarowversion.original不妨缩写为cmd.parameters.add("@customerid", oledbtype.char, 5, "customerid").sourceversion = datarowversion.original一致地当增添参数后赶快举行树立参数的值时,也不妨举行一致以次缩写mydataadapter.selectcommand.parameters.add("@categoryname", oledbtype.varchar, 80).value = "toasters"mydataadapter.selectcommand.parameters.add("@serialnum", oledbtype.integer).value = 239(消息整治来自msdn)