如何解決,關於判斷用戶是否已輸入過資料..謝謝

sql2="select sdgendr from qtest where userid="+userid;
System.out.println(sql2);
ResultSet rs = stmt.executeQuery(sql2);
while(rs.next()){ <-----當沒有相關的id時,就跳到catch
System.out.println("Yes");
int test = rs.getRow();
System.out.println(test);

if(test==0){
String sql="insert into qtest(age,sdgendr,why_reading1,why_reading2,now1,userid) values ('"
+age
+"','"
+sdgendr
+"','"
+why_reading1
+"','"
+why_reading2
+"','"
+now
+"','"
+userid
+"')";
String sql1="insert into wtest(userid) values('"+userid+"')";
System.out.println("sql="+sql);

stmt.executeUpdate(sql);
stmt.executeUpdate(sql1);

rs.close();
stmt.close();
conn.close();

請問如何修改,還有close()這樣寫法正確嗎？