MySQL

: https://dev.mysql.com/downloads/mysql/(Community edition open source free)Data redundancy: Two tables contain the same field, in layman's words is redundant data;Data loss integrity: data loss;Primary key: Uniqueness, (null primary key, i.e. loss

MySQL> Count counts the number of rows, you can find out how many data The number of the sum statistic column average of the AVG statistic column Max Search Column Maximum mid-extract characters from text UCase to replace all

1. Increase:Insert into Values (value, value, value ...) Insert into Values (Value, value, Value ... ), (value, value , value ...) Insert into Select from table2. Delete:Delete from Table Delete from where id=1 and name='Alex'3.

1. What is a database?commonly known as data warehouses, software (or programs) that facilitate the management of data2.MySQL Getting Started1. Download the website2. Install MySQLDouble-click the installation directly, but note that the installed

At work, you need to look at MySQL's top 20 slow SQL, optimized one by one, plus the necessary indexes.But found that the slow query log is not turned on:Mysql> Show variables like "%query%";+------------------------------+--------------------------+

First, the ViewA view is a virtual table (not a real one), which is the essence of getting dynamic datasets and naming them based on SQL statements. Users can only use "name" to get a result set and use it as a table.Select * from (Selectfromwhere

Incoming parameters latitude 40.0497810000 longitude 116.3424590000/*The parameter passed in is latitude latitude longitude asc ascending from near to far desc descending from far to near*/SELECT*,ROUND( 6378.138 * 2 *ASIN( SQRT(

This example is CENTOS7 version: MySQL is mysql-5.5.56.tar.gz1. Uninstalling the existing database on the serverRpm-qa | grep mariadb # # #查询本机有没有默认的mysql, CENTOS7 version database is MARIADBRpm-e--nodeps # # #有的话卸载掉2. Download the source

MySQL Common operationsAuthorized Superuser:Grant all privileges on * * to ' tangnanbing ' @ ' percent ' identified by ' [email protected] ' with GRANT option;To view the library:show databases;See which libraries show databases;View the table of a

8 ways to optimize a MySQL databaseFont: [Increase decrease] Type: Reprint time: 2013-11-07 I want to commentThis article optimizes MySQL database by 8 methods: Create INDEX, compound index, index does not contain NULL value column, use short index,

Originally Linux under the default is the table name is case-sensitive, with the following settings, you can let MySQL is not distinguished table name casing:1, log in with root, modify/etc/my.cnf;2. In the [Mysqld] node, add one line:

Business scenario: Queries that correlate tables in different databasesFor example, the table to be associated with is: Table B in database A on machine a && b in database B on machine A.In this case, you want to perform "select A.id,b.id from A

It is recently necessary to open the MySQL update log (that is, binary log) under Linux, which can be used to avoid database errors or data loss before being able to revert to the operation. But many of the online posts are copy sticky, even for

In MySQL, there are usually these kinds of constraints:DROP DATABASE mysql_shiyan;删除数据库The primary key (PRIMARY key) is used to constrain a row in the table, and as a unique identifier for the row, the primary key is the key to the exact row in one

Install mydumper and mydumper0.9.1Install the dependency package: Yum install glib2-devel for mysql-devel zlib-devel pcre-devel openssl-devel cmakeDownload the Binary Package: Wget

The difference between timestamp and sqltimestamp calculated by SQL. SQL Calculation of timestamp difference Overview Sometimes we need to find some records by time, for example, calculate the record one hour before the sales time.We can usually

MySql 5.6.36 64-Bit green edition installation graphic tutorial, mysql5.6.36 There are a lot of articles on installing MySQL on the Internet, but I encountered a problem in installing MySQL on my laptop today. Here is the only record. 1, download

How to remotely connect to the MySQL database in Linux, linuxmysql Preface I recently encountered this requirement in my work. It is estimated that the remote connection was completed after more than an hour. A local computer and an ECS are all

Centos7.3 detailed tutorial on installing mysql5.7.18 and centos building ss 1. view the Linux release version [Root @ typecodes ~] # Cat/etc/redhat-releaseCentOS Linux release 7.2.1511 (Core) 2. Download the official MySQL Yum Repository Get Yum

Introduction to the show profile (outdated) of MySQL and its substitution in performance_schema in MySQL 5.7, performanceschema   Source: http://www.cnblogs.com/wy123/p/6979499.html   The show profile command is used to track the resource