--省级 Provincial
--城市 City
create table Provincial(pid int,Provincial varchar(50),primary key (pid))
insert into Provincial values(1,'北京市')
insert into Provincial values(2,'天津市')
insert into Provincial values(3,'上海市')
insert into Provincial values(4,'重庆市')
insert into Provincial values(5,'河北省')
insert into Provincial values(6,'山西省')
insert into Provincial values(7,'台湾省')
insert into Provincial values(8,'辽宁省')
insert into Provincial values(9,'吉林省')
insert into Provincial values(10,'黑龙江省')
insert into Provincial values(11,'江苏省')
insert into Provincial values(12,'浙江省')
insert into Provincial values(13,'安徽省')
insert into Provincial values(14,'福建省')
insert into Provincial values(15,'江西省')
insert into Provincial values(16,'山东省')
insert into Provincial values(17,'河南省')
insert into Provincial values(18,'湖北省')
insert into Provincial values(19,'湖南省')
insert into Provincial values(20,'广东省')
insert into Provincial values(21,'甘肃省')
insert into Provincial values(22,'四川省')
insert into Provincial values(23,'贵州省')
insert into Provincial values(24,'海南省')
insert into Provincial values(25,'云南省')
insert into Provincial values(26,'青海省')
insert into Provincial values(27,'陕西省')
insert into Provincial values(28,'广西壮族自治区')
insert into Provincial values(29,'西藏自治区')
insert into Provincial values(30,'宁夏回族自治区')
insert into Provincial values(31,'新疆维吾尔自治区')
insert into Provincial values(32,'内蒙古自治区')
insert into Provincial values(33,'澳门特别行政区')
insert into Provincial values(34,'香港特别行政区')
--select pid,Provincial from Provincial
create table City(cid int not null,city varchar(50) primary key,pid int foreign key references Provincial(pid))
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1.
死锁原理
根据操作系统中的定义：死锁是指在一组进程中的各个进程均占有不会释放的资源，但因互相申请被其他进程所站用不会释放的资源而处于的一种永久等待状态。
死锁的四个必要条件：
互斥条件
(Mutual exclusion)
：资源不能被共享，只能由一个进程使用。
请求与� ......
