MySQL

#移除主键时需要先解除递增 to release the primary keyALTER TABLE info modify ID int null, DROP PRIMARY keyI. User rights1. Create a userCreate user ' Hanshe ' @ ' 127.0.0.1 ' identified by ' 123 '; --Create User2. Removing usersDrop user ' hanshe ' @ ' 127.0.0.1

LAMP Architecture IntroductionLinux is the operating system Apache is a software that improves Web servicesMySQL is a stored software that saves dataPHP is a scripting languageNote: Apache (httpd) is loaded with PHPPHP is in the form of a module and

Create a tableCREATE TABLE Test (ID Int (TEN) NOT null primary key auto_increment,MD5 varchar (30),subkey Int (15)) Engine=innodb;Modify TableAdding columnsALTER TABLE test add column num int;modifying columnsALTER TABLE test modify column num

1. Download the MySQL repo source$ wget http://repo.mysql.com/mysql57-community-release-el7-8.noarch.rpm2. Install the MYSQL-COMMUNITY-RELEASE-EL7-5.NOARCH.RPM package$ sudo rpm-ivh mysql57-community-release-el7-8.noarch.rpmAfter installing this

1. Date and time formattingSelect Date_format (now (),'%y-%m-%d')as//2018-01 - the2. Date and time formattingSelect Date_format (now (),'%y-%m')as// Output 2018-3, query 11th to 15th dataSelect * from 5//How much, how much to remove. 4. Date of

Enabling the MySQL query cache can greatly reduce the CPU usage of the database server, the actual usage is: Before the start of CPU utilization of about 120%, turned on and dropped to 10%.To view the query cache condition:Mysql> Show variables like

At present, the background database uses an instance to do statistical analysis of data, as the data blowout, a single instance can not do data analysis. So the reading and writing separation began.1. master Configuration[Client]Port=

Connect MySQL database command: mysql-u root-pCreating MySQL Database: Create databaase XX library;To create a MySQL table:CREATE TABLE Db_xx Tables (ID int primary KEY auto_increment,Name varchar (+) is not NULL,Address varchar (+) is not

Select *, (@number: = @number + 1) as number from (SelectU.mobile,u. ' Name ',ROUND((Select sum(R.realamount) fromT_recharge RwhereR.userid=U.id andR.status='1'),2) Rechargesum,ROUND((Select sum(W.realamount) fromT_withdrawal

Download the installation package from the official website: mysql-5.6.33-winx64.zip, unzip to D:\java, then add the extracted Bin directory to the system environment variable Path , enter the MySQL root directory, edit my-default.ini , remove the

1. General sort ASC DESCASC Positive SequenceDESC Flashback-- no more talking here .2. Custom Sortingcustom sorting is sorted according to the specific string (number) order that you want. mainly using the function FIELD

--select * from Multidataviewerinfo where post= ';--select * from Multidataviewerinfo where post= ' C04 ';--delete from Multidataviewerinfo;--Update multidataviewerinfo set post= ' C04 ' where post= ';--Update multidataviewerinfo set date= ' 2018-02-

Create a new web app for the core2.0 project and select Authentication.The way the code automatically creates SQL Server:Services. adddbcontext (options = options. Usesqlserver (configuration.getconnectionstring ("defaultconnection"));Consider SQL

May be in the table in the data to delete a row of data, resulting in an ID vacancy, the following is the solution I used: (Please back up, MySQL backup method see mysql->mysql backup )Use Alter drop to delete the original ID field:ALTER TABLE DROP

Environment:Operating system: CentOS release 6.5Database 1:Version: mysql5.6.37basedir:/usr/local/mysql5637Configuration file Location:/data/mysql5637/my.cnfDatabase 2:Version: mysql5.7.19basedir:/usr/local/mysql5719Configuration file Location:/data/

Unzip the copyMV Mysql-5.7.14-linux-glibc2.5-i686/usr/local/mysqlCreate a MySQL user firstGroupadd Mysqluseradd-r-G mysql-s/bin/false MySQLCreate a MySQL data directory that will be used when initializing the

I. Overview of MYSQL/MARIADBMySQL was developed by my SQL company in 1995, the relational database management software, MySQL development several times after the version replacement, the latest is 5.7ga/8.0dmr,my SQL company itself has also

1, read UNCOMMITTED (row lock)Dirty reads occur, things are not committed and are seen by other things, and uncommitted data is dirty data.2. Read committed (Row lock)A non-repeatable read occurs, and when things start, only the things that have

[MySQL TroubleShooting] Service Startup error, A friend sent a startup error stack. When Skip_Grant_Table is started, no error is reported: The experts in the Group found out that the udf_initv UDF reported an error.   But I still cannot

MySQL: database entry, mysql database entry 1. What is a database? -- Data storage warehouse Database technology is a very important technology in the computer application field. It was developed at the end of 1960s and is the latest technology of