SQL语句的详细操作（一）

SQL基础语句

• create table

create table person(
	id int(10),
	lastname varchar(24),
	firstname varchar(24),
	address varchar(24),
	city varchar(24),
	primary key(id)
)

• insert

insert into person values(1, 'Gates', 'Bill', 'Xuanwumen', 'Beijing');
insert into person values(2, 'Dell', 'Smith', 'Heping', 'Tianjin');
insert into person values(3, 'Tom', 'David', 'Haidian', 'Beijing');
insert into person(id, lastname, firstname) values(4, 'Will', 'John');

• select

select * from person;
select lastname, firstname from peerson;

• distinct

insert into person values(5, 'Han', 'David', 'Zhongyuan', 'Zhengzhou');
select firstname from person;
select distinct firstname from person;

• where

select * from person where city = 'Beijing';

• and&or

select * from person where address = 'Haidian' and city = 'Beijing';
select * from person where address = 'Heping' or firstname = 'David';

• order by

select * from person order by lastname asc;
select * from person order by firstname desc;
select * from person order by city asc, address desc;

在以上的结果中有两个相等的city (Beijing)。只有这一次，在第一列中有相同的值时，第二列是以降序排列的。如果第一列中有些值为 nulls 时，情况也是这样的。

• update

update person set lastname = 'Bob' where id = 3;

• delete

delete from person where id = 4;

delete from person
delete * from person
# 效果一样，但是带*的执行比不带*的快，可以试一下