建立表spa
use mydb1;utf-8
create table employee(id int, name varchar(40),sex varchar(2),birthday date,entry_date date,job varchar(40),salary decimal(8,2),resume text);ci
查看錶string
show tables;table
show create table employee;cli
desc employee;亂碼
修改表date
alter table employee add image blob;select
alter table employee modify sex varchar(4);方法
alter table employee drop sex;
alter table employee character utf8;
alter table employee change column name xingming varchar(40);
rename table employee to emp;
刪除表
Drop table emp;
Insert into employee
(id,name,sex,birthday,entry_date,job,salary,resume) values
(1, 'john', 'a', '1990-10-01', '2014-10-1', 'ceo',10000, 'hello');
insert into employee values(1, 'john', 'a','1999-09-09','1999-09-09','bbb',90,'aaaaa');
插入遇到的問題
ERROR 1300 (HY000): Invalid utf8 character string: '\xA1\xAFaaa\xA1\xAF'
解決辦法:引號問題’ ’這種是GB2312 , ' '這種是utf-8
ERROR 1366 (HY000): Incorrect string value: '\xC4\xD0' for column 'sex' at row 1
解決辦法:show variables like 'chara%';
set character_set_client=gb2312;
該處查看會顯示亂碼
解決方法:set character_set_results=gb2312;
修改表數據:
update employee set salary=10;
update employee set salary=10000 where name='john';
update employee set salary=salary+1000 where name='aaa';
刪除表的記錄
delete from employee where sex='null';
delete from employee; //刪除表的內容,但不刪除定義,不釋放空間
truncate table employee;//刪除內容、釋放空間,但不刪除定義
Drop table emp; //刪除表的內容、定義和釋放空間
select * from student;
條件查詢
select * from student where name='王五';
select name,english from student;
select distinct english from student;
select name,(chinese+english+math) from student;
select name,(chinese+english+math)+10 from student;
select name as 姓名,(chinese+english+math)+10 as 總分 from student; //別名
select name 姓名,(chinese+english+math)+10 總分 from student;
select * from student where english>'90';
select name from student where (chinese+english+math)>200;
select name from student where (chinese+english+math)> '200' //這裏用單引號也是能夠的
select name from student where english>80 and english<90;
select name from student where English between 80 and 90; //這句跟上面那句是同樣的
select * from student where math in(89,90,91);
模糊查詢
select * from student where name like '李_'; (2個字符)
select * from student where name like '李%'; (2個字符以上)
排順查詢
select name,math from student order by math;
select name 姓名,(chinese+english+math) 總分 from student order by (chinese+english+math) desc;
select name 姓名,(chinese+english+math) 總分 from student order by 總分 desc;
select * from student where name like '李%' order by (chinese+english+math) desc;
統計
select count(name) from student;
select count(*) from student;
select count(*) from student where (chinese+english+math)>250;
求和
select sum(chinese),sum(english),sum(math) from student;
select sum(chinese+english+math) from student;
求平均
select avg(chinese) from student;
select avg(chinese+math+english) from student;