資料庫操作：

1.增：

insert into test(nid,name) values(1,'sam'),(2,'eric');  #鍵值對形式插入

insert into test values(3,'alex'); # 預設順序

insert into test(nid,name) select nid,name from test1; #插入另一個表裡的值

2.刪：

delete from test;

delete from test where nid=1;

delete from test where nid between 1 and 7;

3.改：

update test set name='sam' where nid=2;

4.查：

select * from test;

select name from test where nid > 5 and name='sam';