MySQL

Although distinct is a syntax for SQL and does not belong to MySQL, here is an example of MySQL.After so many years of distinct, incredibly has been wrong. Always thought that distinct is the removal of duplicate fields, originally it is to remove

MySQL has a lot of extensions for SQL, some of which are handy, but there are performance issues with some of them being misused, and there are some unintended side effects, like REPLACE into.For example, there is a table: 12345678

Windows 10 Home Chinese version, MySQL 5.7.20,2018-05-07Part.1 the character set encoding of the lookup databaseView MySQL Character set encoding:status CommandLog in to the MySQL server using the command line and enter the status command to view

Key points of knowledge:　　I. Overview of the databaseSecond, MySQL installation and basic management1?? Database overview　1. What is data?The symbolic records describing things are called data, and the symbols that describe things can be either

The origin of database management softwareBased on what we've learned before, data is stored in a file for permanent preservation, without a doubt that a file can only exist on a single machine.If we ignore the efficiency of accessing data directly

Compile and install Zabbix Error:mysql Library not foundI compile the installation of MySQL, compile and install Zabbix, using the compilation options

how MySQL permanently resolves the display garbled by DOS encoded format that causes MYSQⅠ, new file ChangeCode.txtⅡ, paste the following code (function: Modify the default GBK (936) to UTF-8 (65001))1Windows Registry Editor Version5.002 3 4

In the MySQL database, the most commonly used engines are 2: InnoDB and Myiasm. This article will focus on the two engines, and how to choose the engine, and finally, what are the data structures used by these 2 engines?First introduce the InnoDB

Learn last_insert_id First LAST_INSERT_ID has its own storage space, can save a number Returns the value of the self-increment field for the last insert row record without parameters. With parameters, the number you store will be

A power outage or abnormal shutdown can cause table corruption in the MySQL database, especially when the MyISAM table data is large. There are three ways, one way to use MySQL's Repair table SQL statement, the other is to use the myisamchk provided

First, installation environment1. Operating system version: Red Hat Enterprise Linux Server Release 7.2 (Maipo)2. mysql version: Mysql-5.7.20-1.el7.x86_64.rpm-bundle.tarSecond, installation instructions1, the official website about MySQL 5.7 each

Connection Amoeba-mysql appears could not create a validated object, Cause:validateobject failedmysql> start slave;ERROR 1872 (HY000): Slave failed to initialize relay log info structure from the repositoryReason: Check my.cnf, originally did not

Proxysql Introduction: Proxysql is a high-performance MySQL middleware with a powerful rules engine. Detailed Chinese Introduction: Other people write, basically with the official no difference Official Document:

reprinted June 07, 2015 18:22:57 Reprinted from: http://blog.sina.com.cn/s/blog_7cecec9501017cmk.htmlFirst, pre-installation preparation1, download the installation package, can go to MySQL official website www.mysql.com download, 1-1:Landlord Cloud

Network environment: The operating system of the MySQL (MariaDB) server is CentOS 7 MySQL (MariaDB) Server ip:172.16.230.15 Client operating system for Windows R2 Client Host ip:172.16.230.200 In the actual project or

MySQL time-per-hour record number scheme 1:? 1234567 SELECT@rownum := @rownum + 1 AS ID,        CONCAT((CASE WHEN t.hour = 24 THEN 0 ELSE t.hour END),‘:00:00‘) AS TIME, COUNT(*) AS COUNTFROM (SELECT id, HOUR(DATE_FORMAT(createtime,‘%

MySQL Database Basics (v)--sql query one, single-table query 1, query all fieldsUse the asterisk "" wildcard character in a SELECT statement toquery all fieldsSpecify all fields in the SELECT statementSelect from TStudent ;2. Query the specified

MySQL database Advanced (ii)--Custom function One, introduction to custom functionsCustom Functions (user-defined function UDFs) are a way to extend MySQL, with the same usage as built-in functions.Two prerequisites for a custom function:A,

MySQL Database Basics (vi)--SQL INSERT, UPDATE, delete operation one, insert data 1, insert data for all fields of the tableInserting data using a basic INSERT statement requires specifying the table name and the values inserted into the new

Mysql Study Notes (1), mysql Study Notes I have recently encountered some problems in learning MySQL databases, some of which have been solved, and some have not yet found the answer. This article will be used as a study note, and some of the