MySQL

Related content:The meaning of system default database Information_schema,performance_schema,mysql,testStarting Time: 2018-02-23 17:10After the installation of MySQL is complete, there are several databases that come with it:

Preparatory work:　　Worm Copy article table adds data to 1.12 millionSyntax: INSERT INTO TABLENAMEA select * from Tablenameb Non-partitioned query 54s　　Changing an existing table partitionAlter Tablet_articlepartition byRANGE (Aid) (PARTITION

First-level caching:Also known as local cache, sqlsession level cache. The first-level cache is always on, and the data that is queried during the same session as the database is placed in the local cache.If you need to get the same data, take it

A lot of information on the web said there are two ways (must have existing unique key)Use of the on DUPLICATE KEY update in 1.INSERTUse of 2.REPLACEResults can be obtained by:If the A and B fields can determine the uniqueExample:REPLACE into TB

There are two main ways to use MySQL for Python operations: Native Module Pymsql ORM Framework Sqlachemy PymysqlDownload installationPIP3 Install Pymysql #PIP3 command path: Scripts directory under installation path # download

import sysreload(sys)sys.setdefaultencoding( "utf-8" )import requestsimport jsonimport pymysqlconn = pymysql.connect(host=‘localhost‘,port=3306,user=‘root‘,password=‘root‘,db=‘toutiao‘,charset=‘utf8‘)cursor = conn.cursor()url =

Mysql-h 121.30.20-u addata_r-p-parreboehw9mijien_ep6bykoxktikunlmysql-h 121.30.20-u ad_plat_w-p-p2JoYTD3257ZWM5M_I Jhuj9fltnuzcq8umysql-h 121.30.20-u addata_r-p-parreboehw9mijien_ep6bykoxktikunl ad_data-e "SELECT ID, advertiser_id, date,cost,0 as

MySQL is currently one of the mainstream database management systems, is still free of charge.The history of the database, the basic concept is no longer mentioned, in short, the database is the storage of data warehouse, and all we see in fact can

Reprinted from Http://www.cnblogs.com/duhuo/p/5650876.htmlMySQL Query record if there is a timestamp field, the view results inconvenient, can not immediately see the meaning of the timestamp represents, now provides the MySQL format change time

What is a storage engine?For example: A video can be MP4 format or AVI format, but users seem to be similar, the intuitive difference is that occupancy system space and clarity is not the same. Storage engine almost, for MySQL, regardless of what

One. MySQL service installation 1. Download:Http://dev.mysql.com/downloads/mysql2. Installation:The entire directory after extracting the downloaded mysql-5.7.21-winx64 compressed package is placed in your favorite location, I put it in the C:\Users\

String functions (which are primarily used to process strings):Cancat (str1, str2, ... strn) connection string str1, str2 ..., strn as a string;Insert (str, x, Y, instr) starts the string str from position x, and the substring of Y strings is

KING01 and King02 each other as Master-slave[Email protected] ~]# mysql-uroot-pabcd.1234Mysql> show Slave status\g;1. Row ***************************Slave_io_state:waiting for Master to send

MySQL Database service operations# Systemctl Start mysqld//Start# Systemctl Stop mysqld//stop# Systemctl Restall mysqld//restartLog in to MySQL database with a password# mysql-uroot-p ' Initialized random password 'Set User Native login

First, backup1, according to the user name, IP, database name to make corresponding changes, need to note is, do not need to login to MySQL, in the cmd command line execution, take my machine as an example,--cannot log on to MySQL client-- MySQL

First, the primary key index relationship1. Primary key: The only function of a primary key is to uniquely identify a row of data in the table. is divided into a single primary key and a federated primary key:Single PRIMARY key: You can uniquely

Go straight to the point: Create a students table firstCreate TableStudents (IDint Primary Keyauto_increment, ageint, namevarchar( -), Cityvarchar( -)) character SetUTF8;Insert intoStudentsValues(NULL, A,'Zhao Four','Hangzhou');Insert

Optimization of 1.MaxIf there is no index, Max needs to retrieve all the rows to produce the results, which can be optimized by indexing:CREATE INDEX on products (price); Index the price in the Products tableIn this way, querying the maximum value

About mysql startup --- mysqld_safe mysqld from pid file * ended, Let me first talk about how to install mysql: 1. At the beginning, installing mysql is a software package that can be decompressed. I decompress it, copy it to the/usr/local/directory,

MySQL and mysql 1. Concept A set of one or more SQL statements!Transactions: a collection of operations. They are born together. Either the execution is successful or the execution fails.2. Transaction Features ACIDA: The Atomicity is complete and