好久不写简书了，今天遇到一个挺奇怪的问题，如下：
ResultSet rs = stmt.executeQuery("select * from xxx");
ResultSet rs2 = stmt.executeQuery("select * from xxx");
int countWb =0;
while (rs.next()) {
countWb = rs.getRow();
}
while(rs2.next()){
tradeDate=rs2.getString("xxx");
}
执行到while(rs2.next()){ 的时候就报Exception in thread "main" java.sql.SQLException: Statement has already closed.
中间没有关闭Statement ，
尝试修改代码顺序如下：
ResultSet rs = stmt.executeQuery("select * from xxx");
int countWb =0;
while (rs.next()) {
countWb = rs.getRow();
}
ResultSet rs2 = stmt.executeQuery("select * from xxx");
while(rs2.next()){
tradeDate=rs2.getString("xxx");
}
跑通成功，同一个stmt，执行完一次查询后，会关掉查询的入口，rs2.next()就会报错，所以rs2.next()运行之前在打开一次查询入口，即执行ResultSet rs2 = stmt.executeQuery("select * from xxx");
就可以了。
