this easy thing do, i'm doing first vb project i'm not sure how 100%, apologies in advanced if following problem simple.
basically, need is, when loading database table ultragrid, need retrieve maximum integer stored in field.
to explain more clearly, each record in database has it's own id number, need iterate each record , find 1 highest id number, , return id, can used in other calculations.
i know can use sql = select max(supportid) tblincidents example retrieve highest id number stored in table.
so, how go declaring result of (so, highest id number) variable can firstly display in messagebox prove me query has worked, , secondly can use variable means of using id throughout code?
an example; code save new record tblincidents table.
private sub btnsave_click(sender object, e eventargs) handles btnsave.click dim incidentsolved boolean = false if cboxsolved.checked incidentsolved = true end if if txtclientsave.text = "" msgbox("client name cannot blank") elseif rtbproblem.text = "" msgbox("problem cannot blank") elseif cboxsolved.checked = true , rtbsolution.text = "" msgbox("please enter solution") else database.savenewincident(txtclientsave.text, dtpstart.value, dtpend.value, rtbproblem.text, dtpstarttime.value, dtpendtime.value, cboxsolved.checked, rtbsolution.text, _con) txtclientsave.text = "" rtbproblem.text = "" rtbsolution.text = "" dtpstart.value = date.today dtpend.value = date.today dtpstarttime.value = datetime.now dtpendtime.value = datetime.now cboxsolved.checked = false end if end sub database function called
public shared function savenewincident(byval clientname string, datestart date, dateend date, byval incidentproblem string, byval timestart string, byval timeend string, byval incidentsolved boolean, byval incidentsolution string, _con oledbconnection) dim tr oledbtransaction = nothing try tr = _con.begintransaction() dim dc new oledbcommand dc.connection = _con dc.commandtype = commandtype.text dc.commandtext = "insert dbo.tblincidents values(?, ?, ?, ?, ?, ?, ?, ?, ?)" dc.transaction = tr dc.parameters.add("@clientname", oledbtype.varchar).value = clientname dc.parameters.add("@datestart", oledbtype.date).value = datestart dc.parameters.add("@dateend", oledbtype.date).value = dateend dc.parameters.add("@incidentproblem", oledbtype.longvarchar).value = incidentproblem dc.parameters.add("@timestart", oledbtype.varchar).value = timestart dc.parameters.add("@timeend", oledbtype.varchar).value = timeend dc.parameters.add("@incidentsolved", oledbtype.boolean).value = incidentsolved dc.parameters.add("@incidentsolution", oledbtype.longvarchar).value = incidentsolution dc.executenonquery() tr.commit() msgbox("save successful") catch ex exception mdinit.errorlog(ex.message, ex.stacktrace) msgbox("failed save data, refer error log") tr.rollback() end try end function
what can in vb.net define sqlcommand require sql connection attached - since query returns single value able execute executescalar return single value eg
dim cmd new sqlclient.sqlcommand("select max(billid) tblrecurring",connectionstring) then
cmd.connection.open and
dim x maxid = cmd.executescalar and finish off
cmd.connection.dispose of course
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