MySQL

MySQL Database Search Example exercise (basic exercise):The MySQL database is built with two tables, with the following examples:CREATE TABLE Student (Stuno CHAR (8) PRIMARY KEY,Stuname VARCHAR () not NULL,Stuage TINYINT not NULL,Stusex

Connect MySQL User: mysql-u root-p Enter passwordCreate DATABASE: "Database name"Copy data: Navicat Transfer data functionProblems that occur during the process:1, open the table, reported 1018,can ' t read dir of '. xxxx ' (errno:13)

1 Reference documentsHttps://dev.mysql.com/doc/refman/5.7/en/source-installation.htmlHttps://dev.mysql.com/doc/refman/5.7/en/installing-source-distribution.htmlHttps://dev.mysql.com/doc/refman/5.7/en/source-configuration-options.html2 安装2.1 打开防火墙3306

ProblemThe Bin-log backup/restore database needs to be turned on, but because the store itself Bin-log saved is too small, and the collation is not good, so you create a new/data/binlog to save the binary logAfter the/ETC/MY.CNF has increased the

0 Select Now ()　　Displays the current time.1 Select char_length (' Andyqan ')　　Displays the character length.Date of 2nd format Select Date_format (now (), '%y-%m-%d ')3 Add/Decrease Date Time Select Date_add (now (), Interval 1 day)4 Type

JMeter---mysql pressure testone, add MySQL drive jar packageAdd a jar package on the test Plan pagesecond, add MySQL connection configurationAdd thread group Right-click-Add (add)-config Element (config element)-->JDBC connection ConfigurationCore

Date-time functions1. Get the current date and timeSELECT now (), Sysdate (), Current_timestamp () from DUAL2. Get the current dateSELECT curdate (), Current_date () from DUAL3. Get the current timeSELECT curtime (), Current_time () from DUAL4.

#创建用户CREATE USER ' zzq ' @ ' localhost ' identified by ' zzq ';#flush the Privileges command essentially extracts the user information/permission settings from the current users and Privilige tables from the MySQL library (the built-in library of

MySQL 5.7.8 begins to support JSON types.CREATE TABLE T (ID int,js json,primary KEY (' id '))Inserting dataINSERT into t values (1, ' {"A": 1, "s": "abc"} ')INSERT into t values (2, ' [1,2,{' a ': 123}] ')INSERT into t values (3, ' "str")INSERT into

Create a stored procedureCREATE PROCEDURE myprocess ()BeginEndTo avoid a semicolon (";") in the stored procedure In the concluding sentence, we use a delimiter to determine whether the command is over.So we can use the $ sign as a closing (or

Keepalived is responsible for failover, and the consistency of data between nodes after failover depends on the specific replication mode.Whether it is master-slave, a master multi-slave or dual-master, the number of cluster nodes, master-Slave

Date_format (Date,format) function Placeholder Description %a Abbreviated Day of the week (Sun .....) Sat) %b Abbreviated month (Jan .....) DEC) %c Month in number form (1 ..

Preface: The Knowledge of explain (executive plan) has been studied, and the index is optimized and analyzed by explain.0. PreparationFirst create three tables: tb_emp (Staff table), tb_dept (departmental table) and Tb_desc (description table)1)

1. ReasonThe failure of the company server and the abnormal shutdown caused the database to start failing.Error message[[email protected] dmp]#/etc/init.d/mysqld startStarting MySQL. error! The server quit without updating PID file (/opt/mysql/data/1

Composite Index principle:The leftmost prefix principle:Index (A,B,C)1, each query must have a, such as AB,AC,ABC, if not a, only the BC query will expire2, query with or, query invalidation3, the query with%*, invalid query.4, where a=* and B > and

MysqlData optimizationBasic steps for slow query optimization0. Run first to see if it is really slow, note the setting Sql_no_cache1.where condition single Check, lock minimum return record table. This sentence means to apply the where of the query

Script Implementation#!/bin/bashFor db_name in ' mysql-e "show databases;" | Sed 1d 'DoMkdir-p/backup/$db _nameFor table_name in ' MYSQL-E ' show tables from $db _name "|sed 1d"Do/application/mysql/bin/mysqldump--master-data=2 $db _name $table _name

Reference: https://www.linuxidc.com/Linux/2016-09/135633.htmOne, Master master server Configuration (192.168.1.3) 1. Edit my.cnf (Command Find file location: Find/-name my.cnf) vi/etc/mysql/my.cnf added in [mysqld]: Server-id = 1log _bin =

Directory:1. Constraints 2. ALTER TABLE3. VIEW1. ConstraintsDescription: SQL constraints are used to specify the data rules in the table, and if there is a violation of the data behavior of the constraint, the behavior will be constrained to

#!/bin/BashEcho-E ['Date+"%y-%m-%d%h:%m:%s"'] Start#system Time Time=`Date+"%y-%m-%d"' #host iphost="127.0.0.1"#database Backup Useruser="Root"#database Passwordpasswd="yourpasswd"#Create a backup directorymkdir-p/backup/db/"$time"#list Database