MYSQL Use

From ElectroDragon
Jump to navigation Jump to search

Operations

  • Update: UPDATE mysql.user SET Password = PASSWORD('password') WHERE User = 'root';

Database

  • CREATE DATABASE demodb;

Tables

create tables

  • CREATE TABLE table_name (column_name column_type);
  • Example 1
CREATE TABLE test1 (
test VARCHAR(100)
);
  • normal: CREATE TABLE stock (id INT AUTO_INCREMENT PRIMARY KEY, name VARCHAR(255), date DATE(255), share INT(100));
  • datetime, varchar, float, int: CREATE TABLE stock (id INT AUTO_INCREMENT PRIMARY KEY, name VARCHAR(255), date2 Datetime, price FLOAT(50,3), share INT(100));
  • CREATE TABLE sum1 (id INT AUTO_INCREMENT PRIMARY KEY, name VARCHAR(255), total_share INT(100), total_cost FLOAT(50,3), avg_price FLOAT(50,3));

Data Type column_type

  • VARCHAR(100) - 0-65535 字节 变长字符串
  • DATE - 3 1000-01-01/9999-12-31 YYYY-MM-DD 日期值
  • INT - 4 字节 (-2 147 483 648,2 147 483 647) (0,4 294 967 295) 大整数值
  • float(50,3)

show tables

  • show tables;

table insert

  • insert into stock(name, date2, share) values ('DBC', '19600101', 1);
  • insert into stock(name, date2, share) values ('DBC', '1960-01-01', 2);

example data

  • insert into stock(name, date2, share, price) values ('DBC', now(), 1, 14.3);
  • insert into stock(name, date2, share, price) values ('DBC', now(), 2, 14.87);

ignore

  • insert ignore into sum1 (name) values ('test2')

table drop

  • drop table stock;

table select

  • SELECT * FROM stock.stock;
  • SELECT User, Host, authentication_string FROM mysql.user;
INSERT INTO sum2(name, total_share, total_cost, avg_price)
SELECT name, 
SUM(share) 'total_share', 
round(SUM(price * share),2) 'total_cost', 
round(SUM(price * share)/SUM(share),2) 'avg_price' 
FROM stock 
GROUP BY name;

table delete

  • DELETE FROM stock WHERE name = 'DBC';
  • DELETE FROM stock WHERE ID = 3;

Column

Add

  • ALTER TABLE `test` ADD COLUMN `type` VARCHAR(10) NOT NULL DEFAULT '0' COMMENT '0为添加1为编辑'
  • ALTER TABLE `test` ADD COLUMN `type` VARCHAR(10)
  • After certain column
ALTER TABLE `sum1`
ADD COLUMN `type` VARCHAR(100) NOT NULL DEFAULT '0' COMMENT '0为添加1为编辑' AFTER `column_name`;
  • Simple after certain column
ALTER TABLE `sum1`
ADD COLUMN `type` VARCHAR(100) AFTER `name`;

Check

  • show fields from sum1;

Change

  • alter table sum1 change avg_buy avg_buy float(50,3);

Column Update

  • Add column
ALTER TABLE vendors
ADD COLUMN phone VARCHAR(15) AFTER name;


ALTER TABLE vendors
ADD COLUMN last_buy VARCHAR(15);


ALTER TABLE stock 
ADD COLUMN last_buy Datetime;


alter table sum1 
add column last_price float(50,3);


  • drop
alter table stock 
drop column last_buy;

Cell

Content Update

Simple Update

  • update sum1 SET type='D-B-' where name='BLV';
  • update stock set date2='20190401' where id=29;

SUM

  • update stock, sum1 set sum1.total_share= (select SUM(share) from stock where sum1.name=stock.name);
  • update stock, sum1 set sum1.total_cost= (select round(SUM(price * share),2) from stock where sum1.name=stock.name);
  • update stock, sum1 set sum1.avg_price= (select round(SUM(price * share)/SUM(share),2) from stock where sum1.name=stock.name);

Conditional Update by IF

  • update sum1 set sum1.avg_buy= (select round(SUM(if(share>=1, price * share, 0)),2) / SUM(if(share>=1, share, 0)) from stock where sum1.name=stock.name);

Other operations

  • Make change: FLUSH PRIVILEGES;
  • service mysql restart
  • systemctl start mysql
  • systemctl enable mysql


Output - dump

  • mysqldump -u root -p test>test.sql

Input

  • mysql -u root -p
  • create database stock
  • exit
  • mysql -u root -p stock < stock.sql

Workflow

Example for mediawiki:

  • mysql -u root -p
  • show databases;
  • use edwik;
  • show tables;
  • SHOW COLUMNS FROM page;
  • select * from page where page_title='RISC-V';
  • delete from page where page_id=4975;

Docker

dump sql

  • docker exec db sh -c 'exec mysqldump -uroot -ppassword wordpress' > /web/import/test2.sql

import sql

  • docker exec -i some-mysql sh -c 'exec mysql -uroot -p"$MYSQL_ROOT_PASSWORD"' < /web/import/blogdb.sql