Acquaintance Database
Why use a database
First, there will be files and programs on a single machine is very unreasonable.
Second, the file operation is a very troublesome thing
So there have been a new concept ---- database
You can be understood as a database that can work independently on a single machine, and can provide us with efficient and convenient way data is a tool of CRUD.
So to help us solve the problem above, if all the data is stored on a separate machine, and provides services to users machine just to store the code you write.
Database of advantages:
1 program stability: a machine where the service is so Renyiyitai collapse will not affect the data and additional services. 2 data consistency: all the data are stored together, all the program data operations are unified, it will not appear data inconsistencies 3 Concurrency: concurrent database can be a good support for all database operations procedures through the network, and the database itself supports concurrent operation of the network, do not need to write our own socket 4. efficiency: use the database CRUD data efficiency to be higher than many of our own process files
Acquaintance MySQL
Database Management Software Category
There are many tools to manage data, more than a mysql. Features access to data according to their division is divided into relational and non-relational.
Can be understood as a simple, requires a relational database table structure, non-relational databases is a key-value store, the table structure is not
Relational databases: MySQL, db2, split, Oracle , sql server
non-relational database: MongoDB (document database very close relationship type of non-relational databases), Redis, memcache
Relational databases are usually table structure, which means you are using a relational database table when the first step is to determine the structure
There are certain types of fields: the name string stored passwords stored in digital memory with a birthday date
MySQL
MySQL can actually see it as a software support remote file operations
Library folder >>>
Table >>> file
>>> record data in a file line by line, called a section of the recording
Header is the first row of data table
Field Name Field Type +
Download and install
mysql installation package provide open source operating system on each of us, including ios, linux, windows.
mysql installation, start-up and basic configuration - linux version (https://www.cnblogs.com/Eva-J/articles/9664401.html)
mysql installation, start-up and basic configuration - mac version (https://www.cnblogs.com/Eva-J/articles/9664401.html)
mysql installation, start-up and basic configuration - windows version (https://www.cnblogs.com/Eva-J/articles/9669675.html)
ps: do pre-configured MySQL when the terminal is recommended that you run as administrator
Windows + r to start an ordinary user
MySQL first met when landing is not directly enter a password
MySQL sql statement is a semicolon does not knock you completely do not enter a semicolon default clients will continue to let you enter
Client landing
mysql -h 127.0.0.1 -p 3306 -uroot -p
can be abbreviated
mysql -uroot -p
If you do not enter a password for the user name default is landed guest mode function can be used in very few
clients logout
Exit;
quit ;
see all the databases
show databases;
view a process
tasklist | findstr name
to kill the process
taskkill / F / PID process ID
Production environment variable
to the path where the startup files added to the system's environment variable
Note: After configuring must restart the mysql server and cmd terminal
will be made into a mysql system service
production system must be a terminal services cmd administrator
mysql - install
Change passwords
without a password
mysql -uroot -p password 123
when there is a password
mysqladmin -uroot -p123 password 321
when a command is entered incorrectly when you can use \ c cancel the previous command cancel
password cracking
service has been launched in the first end stopped
1. skip username password authentication start the server
mysql --skip-grant-tables skip start the server authorization table
2. modify the administrator password corresponding to the user
update mysql.user set password = password (123 ) WHERE user = 'the root' and Host = 'localhost';
3. the server again to close the current username and password verification as to start
4. in the normal manner username and password server connected mysql
Profiles
\ s View mysql server simple configuration
suffix configuration files usually are ini the end of the
mysql configuration file that comes not to modify
, but can create a configuration file my.ini
mysql server will automatically load when you boot my.ini configuration within the configuration file
after completing first need to modify the configuration file server restart to take effect
modified the configuration file must restart the server
The basic operation of the database
object is similar to a folder
by
create database db1;
investigation
show databases; check all
show create database db1; single check
changes
alter database db1 charset = 'gbk' ; modified encoding
puncturing
drop database db1; deletion library
table
creating table when you need to specify the library
specify the library: use library name
View current database: select database ()
by
create table userinfo (id int, name char);
check
show tables; view a library of all the tables below
show create table userinfo ;
desc UserInfo; <==> descirbe UserInfo;
Change
alter table userinfo modify name char (32 );
puncturing
drop table userinfo;
recording
create one or specify an existing library
switch to this library to create the table
and then the operation record
Create Database DB1;
Create Table UserInfo (ID int, name char (32), password int) ;
increasing
insert into userinfo values (1, ' yzy', 123); inserting a single data
insert into userinfo values (1, ' zmm', 123), (2, 'czh', 123) ; insert multiple data
check
select * from userinfo; to query all field information
select name from userinfo; query specified field information
select id, name from userinfo where id = 1 or name = 'yzy'; information field with filter conditions
change
update userinfo set name = 'haha' where id = 1; a modified data field information
update userinfo set name = 'zmm' , password = 999 where id = 1; modify data fields plurality
puncturing
delete from userinfo where id = 1 ; delete the specified qualified data
delete from userinfo; will delete all data in the table