java - stack on insert or update sql table on a user -

hello trying create program has users , each user can calculate payment due pay per hour value , how many hours has worked.

i stacked on button adds hours specific user or updates

usernamegl --> global variable (public static string usernamegl ="";) connect() --> method (workes!)

i using access db , java

    private void addbt_actionperformed(actionevent e) {     double hours1 = 0.0;     double hourstable = 0.0;      hours1 =             double.parsedouble(joptionpane.showinputdialog(this, "how many hours did u work?", joptionpane.question_message));      //establish connection     connect();      try {         resultset result;         statement state = conn.createstatement();         string sql = "select att.hours att att.id = users1.id , users1.username='" + usernamegl + "'";         result = state.executequery(sql);          if (result.next()) {             hourstable = result.getdouble("hours");             if (hourstable == 0) {                 sql = "insert att (hours) values (" + hours1+")";                 result = state.executequery(sql);                  string hoursstring = tostring().valueof(hourstable);                 currenttf.settext(hoursstring);              } else if (hourstable > 0) {                 double total = hourstable + hours1;                 sql = "update att set hours= (" + total + ") hours = (" + hourstable+")";                  string hoursstring = tostring().valueof(total);                 currenttf.settext(hoursstring);             }          }       } catch (sqlexception f) {     } }