顯示所有數據庫 show databases;
創建數據庫 create dababase stu;
刪除數據庫drop database stu;
切換到數據庫use stu;
取得當前的數據庫,帶（）表示函數:select database();
創建表（要切換到數據庫中）
mysql> create table stu_info(
-> stu_id int(8),
-> stu_name varchar(48),
-> stu_sex char(2),
-> stu_age int(8));
查看錶的結構
mysql> desc stu_info;
+----------+-------------+------+-----+---------+-------+
| Field |
Type
| Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| stu_id |
int(8)
| YES
|
| NULL
|
|
| stu_name | varchar(48) | YES
|
| NULL
|
|
| stu_sex |
char(2)
| YES
|
| NULL
|
|
| stu_age |
int(8)
| YES
|
| NULL
|
|
+----------+-------------+------+-----+---------+-------+
4 rows in set (0.00 sec)
刪除表
drop table stu_info;
查看數據庫中所有的表show tables;
主鍵 primary key
增加字段 alert table stu_info add column stu_card varchar(20);
刪除字段alter table stu_info drop column stu_card
;
修改字段 alter table stu_info modify column stu_id int(20);
delete from stu_info where []
insert into stu_info() values ()
select * from stu_info where []
mysql 分業技術 選擇從第1條開始的3條數據
select * from stu_info limit 0,3 ;
選擇從第1條開始的3條數據
select * from stu_info limit 5,3 ;
直接從文件中讀取sql語句然後在mysql中執行
/. d://che//mysql1//mysql.sql
例如
mysql.sql文件中有
use student;
select * from stu_info;
執行 /. d://che//mysql1//mysql.sql後結果爲
Database changed
+--------+----------+---------+---------+----------------+--------------+
| stu_id | stu_name | stu_sex | stu_age |
stu_adr
| stu_birthday |
+--------+----------+---------+---------+----------------+--------------+
|
1 | 車燕兵 |
男
|
25 | cheyanbing.com |
2009-01-02 |
|
2 |
che
|
man
|
23 |
gfdfgdsf
| 2008-12-23 |
|
3 |
che
|
man
|
23 |
gfdfgdsf
| 2008-12-23 |
|
4 |
che
|
man
|
23 |
gfdfgdsf
| 2008-12-23 |
|
5 |
che
|
man
|
23 |
gfdfgdsf
| 2008-12-23 |
|
6 |
che
|
man
|
23 |
gfdfgdsf
| 2008-12-23 |
|
7 |
che
|
man
|
23 |
gfdfgdsf
| 2008-12-23 |
|
8 |
che
|
man
|
23 |
gfdfgdsf
| 2008-12-23 |
|
9 |
che
|
man
|
23 |
gfdfgdsf
| 2008-12-23 |
|
10 |
che
|
man
|
23 |
gfdfgdsf
| 2008-12-23 |
|
11 |
che
|
man
|
23 |
gfdfgdsf
| 2008-12-23 |
|
12 |
cyb
|
man
|
23 | jiangxiganzhou |
2009-02-21 |
+--------+----------+---------+---------+----------------+--------------+
12 rows in set (0.00 sec)
排序方式
asc 按升序
ascend升序
desc 按降序 descend降序
select * from stu_info order by stu_id asc, stu_age
desc;//先按學號升序，再按年齡降序排
常用函數
計算記錄的行數 count()
select count(*) from
stu_info;//求所有記錄的條數,可以加條件表達式
select count(stu_sex) from stu_info;//注意當stu_sex爲空的時候，不會被計算進去
select count(*),count(stu_sex) from
stu_info;
+----------+----------------+
| count(*) | count(stu_sex) |
+----------+----------------+
|
7
|
1 |
+----------+----------------+
對字段求和 sum()
select sum(stu_age) from
stu_info;//字段只能是數字型，不能爲其他類型
+--------------+
| sum(stu_age) |
+--------------+
|
175 |
+--------------+
求平均數函數 avg()
select avg(stu_id) from
stu_info;//空字段不參與求平均
+-------------+
| avg(stu_id) |
+-------------+
|
4.0000 |
+-------------+
日期函數
select now();
+-------------+
| avg(stu_id) |
+-------------+
|
4.0000 |
+-------------+
將日期轉換爲天數 to_days()
select to_days(stu_birthday) from
stu_info;
+-----------------------+
| to_days(stu_birthday) |
+-----------------------+
|
733774 |
+-----------------------+
數學函數
abs()
mod()
round()
字符串函數
length(str)
left(str,len)
right(str,len)
substring(str,pos,len)//下標從1開始
ascii(str)
concat(str1,str2,...)
創建外鍵關聯
create table employee(
id int primary
key,
dep_id int,
name varchar(20),
constraint fk_emp_dept_id foreign key(dep_id)
references department(id));
//constraint約束
刪除外鍵關聯關係
alter table employee drop foreign key
fk_emp_dept_id;
再加drop index fk_emp_dept_id on employee;
外鍵所在的表叫父表，該表叫子表，
以後操作的時候刪除父表id要同時刪除子表的記錄，否則麻煩就大了 。
修改外鍵
alter table employee add constraint fk_emp_dept_id foreign
key(dep_id) references department(id);
顯示用於創建給定表的CREATE TABLE語句
show create table employee;
刪除主鍵
alter table stu_info drop primary key ;
創建主鍵
alter table stu_info modify stu_id int primary key;
建立索引
create index emp_index on employee(name);
刪除索引
drop index emp_index on employee;
多表聯合查詢
select employee.id,employee.dep_id，department.id,department.name
from employee,department where employee.dep_id=department.id;
數據庫備份
//注意一定要在dos下操作，不能在mysql客戶端操作
備份一個數據庫
mysqldump -u root -p --opt
student>d:/che/test.sql
opt表示優化數據庫
備份所有數據庫
mysqldump -u root -p
--all-database>d:/che/all.sql
備份數據庫中的單個表
mysqldump -u root -p --opt student
stu_info>d:/che/stu_info.sql
備份數據庫中的多個表
mysqldump -u root -p --opt student stu_info
employee>d:/double.sql
數據庫恢復
恢復一個數據庫
mysql -u root -p student <d:/che/test.sql
恢復所有數據庫
mysql -u root -p <d:/che/all.sql
恢復數據庫中的單個表
mysql -u root -p
student<d:/che/stu_info.sql
恢復數據庫中的單個表
mysql -u root -p
student<d:/che/double.sql
授予權限//如果沒有該用戶則創建該用戶
grant [權限] on [數據庫名].[表名] to ['用戶名']@['web服務器的ip地址'] identified by
['密碼']
with grant option;
所有權限
grant all privileges on student.* to [email protected]
identified by 'cyb';
賦予student數據庫所有權限
賦予部分權限
grant select,alter on student.* to [email protected]
identified by 'cyb';
回收權限
revoke select on student.* from [email protected]
刪除用戶
delete from user where User='cyb'
記得使用commit;
flush privileges;
修改密碼
update user set
password=PASSWORD('cheyanbing')where user='cyb1';
記得使用commit;
flush privileges;
實現將查詢的結果記錄保存到文件中命令
select list from table into outfile '文件名';
例如:
select * from tbl_corporation into outfile 'd:/test.txt';
