摘要:
以下的情况可能出现死锁1.一个对象的同步方法去调用另一个对象的同步方法,同时另一个对象的同步方法也在调用这个对象的同步方法,导致一定几率的死锁,不一定每次都会出现死锁,模拟的代码如下package threadpool;public class DeadThreadDemo { public static void main(String[] args) { new DeadThread(); }}//顾客class Customer{ public synchronized void say(Waiter w ){ System.out.println(... 阅读全文
摘要:
UPDATE cntheater SET title = (SELECT title FROM cntheater_copy WHERE cntheater.id = cntheater_copy.id)将查询结果作为新表在进行子查询select * from(SELECTCOUNT(*) as totalcount,place,title,CONCAT("li" "qw") as name,(select IFNULL(1/0,'yes')) as istrueFROMcntheaterGROUP BY title) as newTab 阅读全文