刪除數據庫表 cit column into next beijing let 語言 values

結構化查詢語言SQL
1.創建表格
create table tablename
(column1 datatype [constraint],
column2 datatype [constraint],
column3 datatype [constraint]);
例
create table employee
(firstname varchar(15),
lastname varchar(20),
age int,
address varchar(30),
city varchar(20));
2 刪除數據庫表格——註意，這裏不要胡記成"delete",那麽，為什麽delete不用呢，原來，其被用到了

刪除數據
drop table tablename
例
drop table employee;
3 數據查詢
select column1 [, column2,etc] from tablename
[where condition];
[order by counmn1[ASC|DESC] [,order by column2[ASC|DESC]]]
例如：
1）select * from employee;
2）select firstname,lastname from employee;
3）select firstname，lastname from employee where age>30;
4 向表中插入數據
insert into tablename
(first_column,...last_column)
values (first_value,...last_value);
例如：
insert into employee
(firstname, lastname, age, address, city)
values (‘Wu’, ‘Jun’, 20, ‘No.11 Beijing Road’, ‘Wuhan’);
5 更新數據
update tablename
set columnname = newvalue [, nextcolumn = newvalue2...]
where columnname OPERATOR value [and|or column OPERATOR value];
例如：
update employee
set age = age+10
where firstname= ‘Li’and lastname= ‘Ming’;
6 刪除數據
delete from tablename
where columnname OPERATOR value [and|or column OPERATOR value];
例如：
delete from employee
where firstname=‘Wu’ and lastname = ‘Jun’;

數據庫編程