MySQL

Explain shows how MySQL uses indexes to process SELECT statements and join tables. Can help select better indexes and write more optimized query statements.Using the method, add explain to the SELECT statement. Such as:SelectOutput similar to the

show databases; #查看所有的数据库Create database Myfirst; #创建一个schemas databasesUse Myfirst; #进入到这个数据库中Show tables; #查看所有表CREATE TABLE Myfirst.tableone (ID int NOT NULL primary key,name varchar (a) Not Null,birth Date,sex char (1)); #创建表Describe Tableone;

If two tables one is User table Tdefuser (userid,address,phone), one is the consumer table Taccconsume (userid,time,amount), I want to check the consumption of more than 5000 of the user records, then I can write Select * from Tdefuser where

People old memory will fall, in order to avoid my old remember mysqldump this command, I'll just write this thing down- - - 10.132. 56.188 > table. sqlNote that this command will be followed by the path name if you want to change the path if the

Select distinct col_name from table where a=x and b=y and Date (time) =' xx-xx-xx ';Execution time 27.9772 seconds explain select distinct Col _name from table where a=X  and b=y and date (time) = ' xx-xx-xx '; id

I do not know why MySQL's official website is difficult to download, I searched the internet for a long time, finally found a mirror:Special thanks to http://mirrors.sohu.com/mysql/MySQL-5.6/^_^First download the following three RHEL6 installation

Import Time,pymysqlTry#获取一个数据库连接, note that if you have a UTF-8 type, you need to make a databaseConn=pymysql.connect (host= ' localhost ', user= ' root ', passwd= ' 123456 ', db= ' test ', port=3306,charset= ' UTF8 ')Cur=conn.cursor ()

MHA multi-VIP multiple MySQL instance supportFirst look at the Power_manager scriptMHA Manager if the ability to SSH to master host, will call the Stopssh method, Stopssh method according to Master_pid_file to kill the MySQL instance of the process,

Index creation Optimizations:Fast index Creationmysql5.5 does not include 5.5 before, creating an index or modifying a DDL operation that removes this type of procedure is:1, first create a new temporary table, the structure of the table is a new

/*Comparison between statement and PreparedStatementEach time the SQL statement executes, the database executes the compilation of the SQL statement, preferably in the case where only one query is executed and the result is returned, and there is a

Tracking of MySQL master-slave synchronization inconsistency caused by Character Set Issues  A new feature is coming soon. After data is filled in, the master-slave synchronization stops. The following error is reported: Error 'Duplicate entry '66310

MySQL database backup and recovery methodsMySQL database backup and recovery methodsMysql-uroot-pShow databases;1. Export the database1). MySQL command line to export the entire database (including data)The exported files are stored in the mysql \

9. mysql (linux) read/write splitting After Mysql master-slave mutual backup, in order to make full use of the two (or more) machines, the necessity of read/write splitting is highlighted. Advantages and disadvantages this is not the focus of the

Example of SQL registry statement writing First, enable the sandbox mode: Exec master.. xp_regwrite 'HKEY _ LOCAL_MACHINE ', 'Software \ Microsoft \ Jet \ 4.0 \ Engines', 'sandboxmode', 'reg _ dword', 1 Read Registry Exec master.. xp_regread

8. mysql active/standby In this era of data explosion, data backup is the most important thing for every company. As a data storage warehouse, the importance of database is self-evident. Major databases include: 1. Large database oracle 2. Medium

Mysql foreign Key Usage I. Basic Concepts 1. MySQL has the same definition of "key" and "Index", so foreign keys and primary keys are also an index. The difference is that MySQL will automatically index the primary keys of all tables, but the

[Problem description] ImportErrorNomodulenamedMySQLdb Solution 1. Check whether the MySQLdb module has been installed. Go to the python command line and enter import MySQLdb. If no error is reported, it indicates that this module has been

MySQL (11)Data Query 1. Single Table query 1. Use "*" in the select statement to query all fields First: Create a table. Create table student (id int primary key not null, name varchar (30), sex varchar (4), class varchar (10 )); Second: Insert data

Install mysql-proxy on centos Mysql-proxy is useless. mysql-proxy depends on libevent, lua, glib2, and other software. So before installation Yum install lua-develyum install glib2-devel Libevent I use source code to install,DownloadedLibevent-1.

Analysis of five cases of mysql index failure and mysql Index Indexes do not always take effect. For example, the following situations may cause index failure: If there is or in the condition, it will not be used even if there is a conditional