MySQL

$arr =array ("A", "B", "1", "2");Assuming the table name is acticle and the field is isread, the table is as follows Id Isread 1 1,3,4 2 A 3 3 We take the

I. Establishment of teacher and student tablesCREATE TABLE Teacher (tid int unsigned auto_increment primary key,Tname varchar (10),Tdesc varchar (10)) auto_increment = 1; Insert into teacher values (null, ' teacher ', ' Professor of Music '), (null,

Body ContentSimulation preparation-How to simulate high concurrent access to a script: Apache installation file Bin/ab.exe can simulate concurrency-C simulates how many concurrent-N requests have been requested for a total of/HTTP scriptsC:\phpstudy\

Linux and Windows environment to build MYCAT data read and write separation prerequisites need: 1. The server is equipped with a JVM virtual machine, which is the JDK. 2. Two MySQL databases have been implemented master-slave replication, reference:

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

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.

The previous article, "MySQL pessimistic lock summary and practice" talked about the MySQL pessimistic lock, but the pessimistic lock is not suitable for any scenario, it also has some shortcomings of its existence,Because pessimistic locks are

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

# # MySQL Database# # # Knowledge Points:1. Data operation increase, delete, change2. FOREIGN KEY constraint requirements3. A one-to-many table relationship4. One-to-one table relationship5. Many-to-many table relationships6. Referential actions for

Thank you for a cup of herbal tea greatly share, a little borrowed!First, the basic operation of the data table　　Data tables and databases and MySQL relationships.MySQL holds many databases, and a database can hold many tables.Add (create table) to

1. Try to avoid using the! = or <> operator in the WHERE clause, or discard the engine for a full table scan using the index.2, to optimize the query, should try to avoid full table scan, first of all should consider the where and order by the

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

First, the experimental principle: 1, the topological structure diagram is as follows:2, Working principle: Save binary log events from the Master of Downtime crashes (Binlog events) Identify slave that contain the latest updates

MySQL Master master sync implementation1, the basic idea is to eliminate the database single point of failure, to ensure high data availability.2, the pre-requirement is not high can be achieved with the main master synchronization, later if not

1, Connection MySQL format: mysql-h host address-u user name-P user Password1. Connect to MySQL on this machine. First open the DOS window, then enter the directory Mysql\bin, and then type the command Mysql-u root-p, enter after the prompt you to

1. Create a MySQL ClusterDownload PXC imageDocker Pull Percona/percona-xtradb-clusterCreate an internal network: For security reasons, you need to create a docker internal network for your PXC cluster instancesCreate command: Docker network Create

The status command is used to view MySQL state informationMysql>Status--------------/usr/local/mysql/bin/mysql Ver14.14Distrib5.5. +, forLinux (x86_64)usingReadLine5.1Connection ID: theCurrent database:current User: [Email

The role of locks: avoid simultaneous changes to the same data object when concurrent requests, resulting in inconsistent data. How to Lock: 1. Transaction T1 make a request to the system before R1 the operation on a data object and lock it L1.2.

When we use the MySQL database, sometimes our program is not on the same machine as the database, we need to access the database remotely. By default, MySQL users do not have remote access permissions.Here are two ways to solve this problem.1.

1. Common arithmetic operators1.1 Operators, functions, notes1.2 Precautions?? (1) integer (bigint) and integer (+,-,) result is bigint;?? (2) floating-point number and floating-point arithmetic (/), the result of the decimal place is the number of