MySQL

(i) about the storage engine 创建合适的索引是SQL性能调优中最重要的技术之一。在学习创建索引之前，要先了解MySql的架构细节，包括在硬盘上面如何组织的，索引和内存用法和操作方式，以及存储引擎的差异如何影响到索引的选择。 MySQL有很多种衍生版本，这些衍生版本支持更多不同种类的存储引擎。本文主要讨论三种MySQL引擎。MyISAM is a non-transactional storage engine that is the default

Increase:All field names are specified in the INSERT statementSyntax:INSERT into table name (field name 1, field Name 2, ...) Values (value 1, value 2, ...) ）；1.1.2 Field name is not specified in INSERT statementIf you do not specify a field name,

Installation Environment:centos:6.8mysql:5.6First, clear the host's own MySQL,Install the tools and libraries needed to compile the source codeYum install gcc gcc-c++ ncurses-devel perlInstall CMake, download the source code from www.cmake.org and

1. Specify the default character set when MySQL database is createdCREATE database $DN_NAME DEFAULT CHARACTER SET utf8mb4 -- UTF-8 Unicode COLLATE utf8mb4_general_ciAnnotations:> utf8mb4 -- UTF-8 Unicode：字符集；mb4是在utf8的基础上支持了imoji表情。>

Reference Link: https://dev.mysql.com/doc/refman/5.6/en/optimize-overview.htmlArticle Summary:Overview:The basic optimization starts from the software level rule, because the software affects the hardware, the high-level optimization starts from the

1.To optimize queries, avoid full table scans, and first consider indexing on the columns involved in where and order by.2.Try to avoid using the! = or <> operator in the WHERE clause, or discard the engine for a full table scan using the

When Mysql updates a field, there are two cases when the length exceeds the limit:1, through the interface update;1) At this time the interface will error: The field exceeds the length value;2, directly execute SQL update;2) SQL does not error,

1 categories of variable 1.1 variables System variables: Global variables: Session Variables: Custom variables: User variables: Local variables: 1.2 Basic introduction to System

1, MySQL int (10)The int type is 4 bytes long, approximately represents the 2^32 number, 10 represents the display length, and the general and fillzero constraints are used together, if the length is not reached, the padding 02-->000000002MySQL

Delete the wrong user table root can not even go up, and then we can understand the root password do not know, forget. Use this method to retrieve root and recreate the deleted user. Fortunately not on the line ... 1. Modify the login settings for

MySQL server is the most popular database management system.A database is a warehouse that organizes, stores, and manages data according to its structure.MySQL database is the data in the form of a table, each behavior record name, each column

Operation of JSON dataCREATE TABLE IF not EXISTS Table_json (id BIGINT auto_increment,json json,primary KEY (id)); ALTER TABLE Table_json Add COLUMN name VARCHAR (GENERATED) always as (Json_extract (JSON, "$.name")) virtual; ALTER TABLE Table_json

Now I have a requirement that there are two projects, one called Project A, one project B, because the user table of A and B's user table are to be implemented the same.For example: I registered in the A project, to be able to login in Project

1, DROP, truncate, delete difference TRUNCATE table is functionally the same as a DELETE statement without a WHERE clause: Both delete all rows in the table. However, TRUNCATE TABLE is faster than DELETE and uses less system and transaction log

Create test dataFully-prepared databasemysqldump --single-transaction --flush-logs --master-data=2 --all-databases --triggers --routines --events --set-gtid-purged=off> backup.sqlAdditional test dataDelete all data in a tableConfirm binary Log save

1. Storage Engine: is a table-level type.2. How to view the table storage Engine:(1), mysql> Show table status in MyDB where Name= ' classes ' \g;1. RowName:classes Table NameENGINE:INNODB Storage EngineVersion:10 current version of the table (multi-

Part of the content is transferred from: https://www.cnblogs.com/wupeiqi/articles/5713323.html★ View1, somewhat similar to the temporary table from the individual name, and then saved in the database, the next time can be accessed directly through

One, MySQL full-scale backup and incremental backup1, the full amount of backup command: /application/mysql/bin/mysqldump-uroot-p123456--lock-all-tables-a-b-f--master-data=2--single-transaction-- Events|gzip

Modifications to the table after creationThe ALTER TABLE statement is used to modify the table after it is created, using the following basic usage:To add a column:Basic form: ALTER TABLE name add list column data type [after insertion position];示例：

Non-stop lock table online master-slave configurationhttp://seanlook.com/2015/12/14/mysql-replicas/ Master never synchronizesHttp://www.rfyy.net/archives/2309.htmlhttp://blog.51cto.com/storysky/259280 About