MySQL

MySQL numeric functionABS (x) returns the absolute value of XCeil (x) returns the smallest integer value greater than XExample:Select Ceil (0.8), ceil (-0.8); The result is 1, 0Floor (x) returns the maximum integer value less than xExample:Select

1.1Multi-instance explanation1.1.1Create an environment configuration file3306 3307 3308multiple mysqld processes (mysqld_safe)Multiple configuration files (port,server_id datadir log-error log-bin socket)Managing multiple sets of data (multiple

As a representative of the relational database, open source MySQL is basically something that a developer must learn and is the most suitable database for personal development--for free.First, go to the official website to download and install MySQL.

MySQL replication is mainly used for MySQL backup or read/write separation. Do the preparation before configuring, configure two MySQL servers, or configure two ports on a single server.Process:A-->change

What is a transaction (transaction)Ensure that the batch operation is either fully executed or not executed at all, maintaining the integrity of the data. That means either success or failure.Transactions can be n-SQL statements (n>=0)Not all

MySQL database uses data types that have Numeric type Integer typeTinyint a tiny integer that occupies 1 bytes by default is the signed integer value range is-128-127 if you need to set an unsigned small integer to be preceded by the

MySQL Master-slave Replication IntroductionIn the current production work, most of the MySQL master-slave synchronization is asynchronous replication mode, that is, not strictly real-time data synchronization.Real-time and asynchronous:    

There are two main ways to handle MySQL transactions.1, with Begin,rollback,commit to achieveBegin a transactionROLLBACK TRANSACTION RollbackCommit TRANSACTION Acknowledgement2, directly with set to change the MySQL automatic submission modeMySQL is

Download imageUsing the docker pull mysql:5.7.21 pull MySQL image, use docker images the view-owned image after the download is successful: ? Downloaded MySQL image. Create a new folder for persistence1. Create a

MySQL Master-Slave synchronizationMySQL AB Replication1. Geo-synchronization of the specified library.2.MySQL---from the implementation of the replication architecture.Read-only control of the 3.MySQL server.Subordinate:When you copy one-way, it is

MyBatis's fuzzy query function is widely used in MySQL database as an example (different databases, some may not support)There are three ways to use fuzzy queries: Direct use of the% stitching string, such as ‘%‘#{name}‘%‘ or "%"#{name}"%" ,

Sometimes, for convenience, some students like to install MySQL through Yum, without setting up a unified file directory and software catalog, then it will bring a lot of trouble for the subsequent maintenance work! Here's a quick introduction to

BackgroundIn the case of e-commerce shopping, when we click on the shopping, the backend service will reduce the inventory operation of the corresponding goods. In the case of single-instance deployments, we can simply use the lock mechanism

Scenario: The external only accesses the primary database (Mysql_master), and multiple database hot backups are made from the database (Mysql_slave). Once the primary database is down, the data is processed from the serverExperimental extension

Before the textUsing JDBC in the previously written Javaweb project, here's a recap and a demo look at the JDBC concept first. A Java database connection, (Java db Connectivity, or JDBC) is an application interface in the Java language that

Compile and install MySQLNote: Compiling MySQL will be more resource-intensive, it is recommended to upgrade the memory to 1-2G under the virtual machineMySQL is a relational database management system developed by the Swedish MySQL AB company and

Today is the 27, tomorrow is 28, one to the Chinese New Year, it is customary to say the lunar calendar, not to say the Gregorian calendar. These two days are very busy, and then a remake.The Linux processing Text tool has three Musketeers, awk,

This problem is due to the fact that the database table is not installed in the data directoryWorkaround:Vi/etc/my.cnfModify the correct datadir= "xxxxx" toThen service mysqld startService MySQL StartAfter normal startup, you will/var/lib/mysql the

First, install the MySQL related package Mysql-5.7.17-1.el6.x86_64.rpm-bundle.tarYou only need to download the unpacked package:mysql-community-client-5.7.17-1.el6.x86_64.rpmmysql-community-common-5.7.17-1.el6.x86_64.rpmmysql-community-libs-

Relational database,1. Create a table 1 create table student (2 sno char (8), 3 sname char (8), 4 sbirth date, 5 ssex char (2), 6 sdept char (30) 7 );    2. delete a table 1 drop table student1;    3. Common Data Types  4. Declare the primary