有关循环的有关问题

有关循环的问题
ResultSet rst=stmt.executeQuery("select num from student;");
   
  //根据结果判断
  while(rst.next())
  {
   
  String num1=rst.getString(1).trim();
  //out.println(num1);
  ResultSet rst1=stmt.executeQuery("select num from u1;");
   
  while(rst1.next())
  {
  //out.println(num1);
  String num2=rst1.getString(1).trim();
   
  if(num1.equals(num2))
  {
  continue;
  }
  else if (!num1.equals(num2))
  {
  } 
   
  }  
  stmt.executeUpdate("insert into u1 values('"+num1+"','"+num1+"');"); 
  out.println(num1); 
   
  }
 我想让外层循环的值与内循环的值一一比较，如果全部都不相等的话就执行后面这个sql语句
stmt.executeUpdate("insert into u1 values('"+num1+"','"+num1+"');"); 
  
绕晕了，麻烦各位指点哈



------解决方案--------------------
bool flag = true;

ResultSet rst=stmt.executeQuery("select num from student;");

//根据结果判断
while(rst.next())
{
String num1=rst.getString(1).trim();
//out.println(num1);
ResultSet rst1=stmt.executeQuery("select num from u1;");

while(rst1.next())
{
//out.println(num1);
String num2=rst1.getString(1).trim();

if(num1.equals(num2))
{
flag = false;
break;
}
}
}
if(flag){
stmt.executeUpdate("insert into u1 values('"+num1+"','"+num1+"');");
out.println(num1);
}