MySQL

The following table is used to adjust a composite index: | Field | Type | Null | Key | Default | Extra | + ------------- + ----------------------- + ------ + ----- + --------- + ------------------ + | pid | int (10) unsigned | NO | PRI | NULL | auto_

With 8 MySQL performance optimization tips, you have completed your brand new applications, and everything works like a charm. To use your network. Everyone is happy. Www.2cto.com then, suddenly, a large outbreak of users killed your MySQL server

[Mysql] MyISAM Table Storage Format MyISAM supports three different storage formats: fixed format, dynamic format, and compressed format (only created using myisampack ). Static table features (fixed format) Static format is the default storage

The specific meaning of the return value of the performance test of the explain SQL statement the specific meaning of the return value of the performance test of the explain SQL statement is as follows: mysql> explain select * from table; + ---- + --

Mysql account management 1. CREATE an account Shell code create user 'jeffre' @ 'localhost' identified by 'my pass'; www.2cto.com 2. delete an account (deleting an account also deletes all its permissions) shell code drop user 'Jeffrey '@ 'localhost'

The following table analyzes the sorting of null values in mysql: t_user: name agezhangsan 1 lisi NULLwangwu 2 www.2cto.com execute the SQL: SQL code select * from t_user order by age; name agelisi NULLzhangsan 1 wangwu 2 In fact, we want to put

Mybatis queries handle input errors. the mysql database is used for processing, and mybatis is used for management. The java background is the spring framework, and the www.2cto.com console displays: 1 There is no getter for property named 'xxxx' in

Mysql5.5 set up master-slave replication 1. note: (1) the Master/Slave server version must be the same (2) to change the root password, do not use the initial password (this is irrelevant to Master/Slave replication, for database security

Wildcard characters: percent, underline, and escape % in the like Statement of MySql indicate any number of characters in the SQL code www.2cto.com select * from user where username like '% huxiao '; select * from user where username like 'huxiao % '

In windows, a data export error occurs in mysqldump. couldn't execute 'show triggers' like '. in windows, a data export error occurs in mysqldump. couldn't execute 'show triggers like 'tb \ _ cate \ _ goos'': cantn't create/write to file 'C: \

Mysql on duplicate key update problem: My database table test has three fields: id int (10), name char (12), testts timestamp; if I want to update the name, the corresponding testts is also updated to the latest timestamp, how do I set it? Create

Mysql Stored procedure Processing dynamic parameter SQL code -- delete drop PROCEDURE if exists up_common_select -- CREATE procedure 'up _ common_select '(in t_name varchar (50) begin declare v_ SQL varchar (500 ); set v_ SQL = concat ('select *

"MySQL server has gone away" reproduction method (PHP) If you want to debug the problem of "MySQL server has gone away", you can reproduce it as follows: modify the configuration file: [html] sudo vi/etc/mysql/my. cnf: [html] [mysqld] wait_timeout =

The difference between horizontal and vertical database splitting (taking mysql as an example): The following table is currently involved in a simple Shopping System: 1. product table (data volume: 10 million, stable) 2. order table (200 million

Mysql limit paging query optimization is generally used for paging query in mysql, and orderby is usually used for sorting queries. However, when the table data volume is large, for example, the query statement segment limit 10000 or 20, the

Mysql scheduled backup operation 1. Create and save the backup file path/mysqldata # mkdir/bak/mysqlbak2, create/usr/sbin/bakmysql file # vi/usr/sbin/bakmysql. sh3. Write the following script [python] #! /Bin/bash # Name: bakmysql. sh # This is a

Use SQL to concatenate the values of multiple queried columns into a single string in MySQL: [SQL] -- Single Column splicing. First, locate a row and add a comma, then the next line of select group_concat (E. SUPPORT) from engines e where E. xa in ('

[MySQL] the InnoDB Storage engine InnoDB is a transaction-safe storage engine, which draws on a lot of Oracle architecture ideas. Generally, in OLTP applications, innoDB should be the first storage engine for core application tables. InnoDB is

Statistical analysis-the statistical analysis module of the mysql cursor project uses stored procedures to collect statistics on data, meeting the needs of users to view report data. I used less mysql cursors before. I wrote a small example to

MySql unlimited classification structureUnlimited classification is a very common application in our development, such as forum sections, CMS categories, and many applications.The most common and simple method is ID, parentID, and name in MySql. The