查询数据库进行登录问题

Question

String passname1;
String password1;
 public String loginInit() throws Exception
 {

 chaxunuser();
 if(passname1.equals(user.getPassname())
   && password1.equals(user.getPassword()))  { 
// selectInfo();
 return SUCCESS;
 }
 else
 return ERROR;
 }
 public String chaxunuser(){ 

try {
//注册数据库驱动程序为Oracle驱动
Class.forName("oracle.jdbc.driver.OracleDriver");
//创建数据库连接。
Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@192.168.90.180:1521:orcl", "training", "training");
//创建一个Statement对象                                                                 
Statement stmt = conn.createStatement();
//执行一条sql查询
System.out.println("select  from tb_user  where userid='"+user.getPassname()+"'");
ResultSet rs = stmt.executeQuery("select  from tb_user  where userid='"+user.getPassname()+"'");
passname1=rs.getString("USERID");
password1=rs.getString("PASS");
rs.close();
stmt.close();
conn.close();
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
return SUCCESS; 
}

Answer 1

ResultSet rs = stmt.executeQuery("select from tb_user where userid='"+user.getPassname()+"'");
passname1=rs.getString("USERID");
password1=rs.getString("PASS");
rs怎么也得判断下if(rs.hasNext)
然后rs.next

Answer 2

rs要向下移动才行
if(rs.hasNext())｛
     rs.next();
    ......
}

Answer 3

while(rs.next()){
    passname1=rs.getString("USERID");
    password1=rs.getString("PASS");
}