MySQL

Small comics Come on, take a look at the little comic book to edify sentimentOK, here's the point. Suppose that you have a table erp if you directly make the following command drop table erp This time all the MySQL related processes will stop until

Brief introduction1 · Index and classification2 · Create and view indexes3 · The concept and characteristics of the transaction4 • Operation of the transaction5 · Summary Expansion : Before you begin to understand the index, learn to

I. OverviewThe previous section describes many of the database optimization measures, but in the actual production environment, due to the performance limitations of the database server itself, it is necessary to optimize the application of the

DQLBasic Query field (column) control 1) Query all columns: SELECT * from table name ; "*" means querying all columns 2) Query the specified column: Select column 1, column 2, column N from table name ; 3) complete duplicate records

First: Chapter One1: Using TransactionsTransaction ; Select * from T1; commit;2: View transaction statusMysql>Show variables like 'autocommit';+---------------+-------+|Variable_name|Value|+---------------+-------+|Autocommit| on |+-------------

Common commands1. Displays the list of databases in the current database server: MySQL> SHOW DATABASES;2. Establish the database: MySQL>CREATEdatabase name;3. Set up the data sheet:MySQL> use library name; MySQL>CREATETABLEVARCHAR(1CHAR);4.

Mysql> grant permissions 1, permissions 2,... Permission n on the database name. Table name to User name @ user address identified by ' connection password ';Permissions 1, Permissions 2,... Permission n represents 14 permissions, such as

There are two ways of MySQL: floating-point and fixed-point. Floating-point numbers include float (single-precision) and double (double-precision), while the number of points is only a decimal representation.Fixed-point numbers are stored as strings

Redo log (redo log)Preface: The difference between the bin log and the InnoDB log file in MySQL has been unclear, and there is always a question in the mind binlog log files can be used forLog backups of the database have been restored, and a redo

Creating an instance: Create TABLE hash_emp ( tid int, tname char (255) ) PARTITION by HASH (TID) partitions 8;View:Select Partition_name,partition_expression,partition_description,table_rows from Information_schema.partitions

1. mysql main storage engine: Myisam,innodb and memory(1) MyISAMIt does not support transactions, does not support foreign keys, especially fast access, there is no requirement for transactional integrity, or a SELECT, insert-based application can

Official Document Address: https://dev.mysql.com/doc/refman/5.7/en/binary-installation.htmlStart installation 1, download MySQL binary package# cd/usr/local/wget https://dev.mysql.com/get/downloads/mysql-5.7/

MySQL Introduction MySQL is a relational database management system, where relational databases store data in different tables rather than putting all of the data in a large warehouse, which increases speed and increases flexibility.

MySQL: Terminating the statement method:1. At the end of the statement, enter a semicolon (;) to indicate the end of the statement2. Using the \g (meaning go)\G Displays the results in a vertical fashion, one value per lineDatabase: A database that

Table sql:CREATE TABLE IF not EXISTS' users ' (' ID 'int( One) unsigned not NULLauto_increment, ' user_group_id 'tinyint(3) unsigned not NULL DEFAULT '2', ' username 'varchar( -) not NULL, ' email 'varchar( the) not NULL, ' password 'varchar( -)

I. Overview 1. Single MySQL Problem1) does not support high concurrency numbers2) Single point of failure3) Loss of data2. master-slave replication Ensure data synchronization between servers (primary means write server, slave to read

1 Download and install the official MySQL Yum RepositoryDownload Install Yum Repository　　Wget-i-C http://dev.mysql.com/get/mysql57-community-release-el7-10.noarch.rpmYum Installation　　Yum-y Install mysql57-community-release-el7-10.noarch.rpmStart

download MySQL Official website Download MYSQL5.7.21 version, link address https://www.mysql.com/downloads/. Download the flowchart as follows: Enter the official dot click community, download the community version. Locate the MySQL Community Server

Start/Stop MySQL Service under MacOSLocal connection MySQL Service, user name: root, Password: abc123$ mysql-hlocalhost-uroot-pabc123Show Database listmysql> show databases;Displaying data tables in a librarymysql> use MySQL;Mysql> Show

Synchronize data from the library on the main library (to have other database servers automatically synchronize data on the data server that is currently being accessed)Structure type of master-slave synchronization1 primary------>1 from (common)