MySQL

Server hardware optimization:1 Better CPU SelectionMySQL has some work that only uses single-core CPUs, such as replicate and SQL. The number of CPU cores is not as good as possible, the server used by MySQL5.5 cannot exceed 32 cores, otherwise

1. If you want to use a function in a MySQL statement, be sure to remember that there is no space allowed between the function name and the parentheses following it. Having space-time lattices can cause syntax errors.2. If you have entered several

1. Synchronizing a small number of librariesBinlog-do-db=db_pxREPLICATE-DO-DB=DB_PX---If you need to update across databases and you do not want to replicate these and new, you should use this optionREPLICATE-DO-TABLE=DB_PX----Allow cross-database

To create a MySQL group and users:-r-g mysql-s/bin/false MySQLTo create a related directory:mkdir -p/data/mysql/mysql3306/{data,logs,tmp}chown -R mysql.mysql/data/mysqlInitialize MySQL:LN -s/opt/mysql-5.7. -LINUX-GLIBC2.

The on DUPLICATE key update syntax is not a standard syntax for SQL, and if specified at the end of a sentence, it updates the contents of the database according to the specified primary key or uniquely labeled indexThe specific action is to see if

Use of 1.insert_select: Copy data from one table to anotherINSERT into students (name,sex,likebooksnum,likesportnum,average)SELECTName,sex,likebooksnum,likesportnum,averageFrom Students_copy;2.regexp: Use of regular expressions, BINARY is a

Directory Migration Shutting down the database serviceservice mysqld stop Copy Databasemv /var/lib/mysql /data/mysql# 或者使用cp -a复制# 这两个命令都会带权限到新目录去 Modifying a configuration file/etc/my.cnf[mysqld]#datadir=/var/lib/mysql

A view is a virtual table that does not actually store data and stores a "functional relationship."Grammar:CREATE VIEW name as SELECT statement.Why does a view store a function relationship?When referencing a view, it looks for related fields based

Master-Slave synchronization, the essence is the use of database logs, the main library data copy to the library, in essence, the use of data replication technology.This article outlines Basic configuration of the main library Basic

MySQL log is divided into error log, binary log, slow query log, query log 1. The error log can be used to view the file of the error log through the following command: Show variables like ' Log_error '; the above command can be used to locate the

Windows environment configuration Mysql 5.7.21 windowx64.zip installation-free tutorial details, 1.download mysql-5.7.21-windowx64.zip mysql from the official website 2. decompress the package to the appropriate location (E: \ mysql). I changed the

Optimize MySQL three simple minor adjustments and mysql adjustments I don't want to be an expert DBA, But when I optimize MySQL, I respect the 80/20 principle, specifically by simply adjusting some configurations, you can squeeze out performance

MySQL advanced query,   Advanced Query Keyword writing sequence keyword execution sequenceSelect: Projection result 1 5 From: locate Table 2 1 Where: first filter 3 2 before grouping Group by: group 4 3 Having: The second filter after grouping 5

MySQL Group Replication configuration, mysqlreplicationMySQL Group Replication MySQL group replication implements Multi-master Update (single-master mode) based on the replication protocol ). A replication group consists of multiple server members,

Summary of execution issues between mysql max and where, mysqlmax Execution problem between mysql max and where Execute SQL: Create table 'grades' ('id' int (20) not null AUTO_INCREMENT, 'student _ id' int (20) not null, 'subobject' varchar (20)

Installation and configuration tutorial for mysql 5.7.20 \ 5.7.21 without installation, 5.7.205.7.21 Download and install mysql 5.7.20/5.7.21 for your reference. The specific content is as follows: 1. Download mysql, Select the operating system and

A Preliminary Study on MySQL statistics and estimation methods, and a preliminary study on mysql statistics   The statistical information in the database describes the data distribution in the table to varying degrees. The execution plan obtains the

Add, delete, modify, and query MySQL DML and DQL, dmldql Add, delete, modify, and query DML and DQL   SELECT * FROM grade -- Add insert -- Adds three data entries to the grade Table.Insert into grade (gradeID, gradeName) VALUES (4, '4 ');Insert into

Advanced query (1), advanced query ( Data TypeInteger intDecimal doubleHigh Precision --- Decimal)Corresponding to the type BigDecimal in Java String: nvarchar (32) varchar charChar: fixed-length string (once the length is set, the space of the

MySQL basic statement and MySQL statement Create a table If it is a keyword, use the key below the back quotation mark ''esc Create table [if not exists] table Name (Field 1 Data Type [constraints, indexes, comments],Field 2 Data Type [constraints,