MySQL

1. Add primary key (primary key index)Mysql>alter TABLE ' table_name ' ADD PRIMARY KEY (' column ')2. Add unique (unique index)Mysql>alter TABLE ' table_name ' ADD UNIQUE (' Column ')3. Add index (normal index)Mysql>alter TABLE ' table_name ' ADD

Display widthThe integer data type in MySQL can specify the display width, and SQL Server does notCreate a tableCREATE TABLE tb_emp (id BIGINT (1))The ID field has a data type of bigint (1), noting the subsequent number 1, which represents the

1. Before practicing a Java Web project, MySQL encoding is set correctly, the server encoding is also set correctly, but when storing data to MySQL, there will be garbled problem, and later found that the MySQL and the server encoding Setup problem,

1: Environment two MySQL server master (mysql): 192.168.1.100From (MySQL): 192.168.1.200 Note: Both MySQL versions must be consistent2: Configure the primary server Mysqld configurationVi/etc/my.cnfServer-id=100 #设置主服务器的ID (the last one to write the

#!/bin/bash#By: sadoc.blog.51cto.com. /etc/rc.d/init.d/functionsMyuser=rootMypass= "123456"Mysock=/var/lib/mysql/mysql.sockmy_start= "Systemctl START mysqld.service"Log_path=/tmp/mysqlMy_path=/usr/bin/mysqldays= ' Date +%f 'second= ' Date +%y/%m/%d-%

To undertake the above: MySQL in the premise of not writing stored procedures or functions, the use of SQL statements to split a string into an arrayThe main idea is actually the same: enough to build a sequence, and then combine the features of

These two days to see the "Build high-performance Web site" This book, feel write is really good, a lot of actual projects will encounter problems are mentioned, today see a most left prefix principle, have heard before, but have not understood,

I experimented with MySQL's trigger today.Mysql> Usetest;DatabaseChangedmysql> descTime ;+-------+---------------------+------+-----+---------+-------+|Field|Type| Null | Key | Default |Extra|+-------+---------------------+------+-----+---------+---

First, create a table (increase)Ii. deletion of the table (deleted)drop table name;Third, modify the table (change)3.1 Modifying a table-adding a column3.2 Modifying a table--modifying the value of a column3.3 Modifying a table--deleting columns3.4

MySQL itself proactively backs up batch commands:Set "ymd=%date:~,4%%date:~5,2%%date:~8,2%"Set "hms=%time:~,2%%time:~3,2%%time:~6,2%"Mysqldump-uroot--password=password weixin> D:\mysql_back\weixin_%Ymd%_%hMs%.sqlCommand explanationTo use mysqldump,

1. Add System pathDownload after installing DMG, it is not possible to use the instructions directly, because the directory is not added to the environment variable Terminal Type cd ~ Touch. Bash_profile Open-e. Bash_profile

1. CREATE USER ' dog2 ' @ ' localhost ' identified by ';Change "localhost" to "%", which means you can log on on any computer, or you can specify that a machine can be logged in remotely;2. GRANT privileges on databasename.tablename to ' username ' @

Mind Mapping650) this.width=650; "src=" Http://pic002.cnblogs.com/images/2012/152332/2012031517135244.png "style=" border:0px; " />IntroducedThe most storage engines used in MySQL are InnoDB and MyISAM. As the default storage engine for MySQL,

Mysql exercises ---- More JOIN operations, ---- moreoperations This tutorial introduces the notion of a join. The database consists of three tablesmovie,actorAndcasting.  Movie Actor Casting Id Id Movieid Title

Mysql exercise ---- SUM and COUNT/zh figure (2 ),World country overview GROUPAndHAVING By includingGROUPSub-statement function,SUMAnd setCOUNTIt is applied to the project group with shared values. When you specifyGroup by continentThe result is

Install Mysql in linux For beginners, Mysql may be rarely installed separately (most of them use integration packages such as wampserver and PHPstudy. Because I am writing php, I won't say much here ). Because it is the first time to install Baidu

Mysql exercises ---- The JOIN operation, ---- thejoin Game Id Mdate Stadium Team1 Team2 1001 8 Jun 2012 National Stadium, Warsaw POL GRE 1002 8 Jun 2012 Stadion Miejski (Wroclaw)

# And $ in mybatis,# And $ in mybatis 1. # When the incoming data is treated as a string, a double quotation mark is added to the automatically passed data. For example, order by # user_id #. If the input value is 111, the value parsed to SQL is

SELECT if_case process function, selectif_case Process Common flow functions in DQL if_case --- Process functions implement conditional Selection in an SQL statement   Employee salaries are classified as follows: mysql> create table

Install mysql basic yum and mysql basic yum 2017-04-I. experiment environment Centos7_x64 Because mariadb is used to replace mysql in centos7 yum source by default, We have to configure the yum source first. Of course, mariadb and mysql are fully