MySQL

1th MySQL architecture and history 1.2 concurrency controlMySQL implements concurrency control at two levels: the server layer and the storage engine layer. Read lock and Write lock:When dealing with concurrent reads or writes, you can solve the

Open a, A, a, b two database connections, B, after opening the transaction, b. Insert a data R and submit, verify the impact on the operation of a Select Select for Update Update R Update R Post Select

1.# Start/Stop serviceNET Start/stop service Name2.# Connection DatabaseMysql-u Root-proot3.# Creating a DatabaseCREATE database name;4.# View all databasesSHOW DATABASES;5.# using the databaseUse database name;6.# Deleting a databaseDROP database

First, you can refer to: https://www.cnblogs.com/flipped/p/6810216.htmlThank you very much at the same time also admire this blogger.This website installs and configures the MySQL, inside content is very whole, but has a little insufficient, is

MySQL deletes data in several cases and whether to free disk space:1, DROP table table_name immediately free disk space, whether it is InnoDB and MyISAM;2. TRUNCATE TABLE table_name immediately frees up disk space, both InnoDB and MyISAM. Truncate

1. Recommended specification for MySQL data modeling:1.1 Fair use bigint (20) numeric type: type: bigint size: 8 byte Range (signed): (-9 233 372 036 854 775 808,9 223 372 036 854 775 807) Range (unsigned): (0,18 446 744 073 709 551 615) Use:

to MySQL website download mysql compiled binary installation package, on the download page select Platform: Option Select Linux-generic, then pull the page to the bottom, 64-bit system download linux-generic (GLIBC 2.5) (x86, 64-bit), 32-bit system

One: IntroductionTheme:Multi-Table Connection queryQualifying Connection QuerySub-queryPrepare table#Build TableCREATE TABLE Department (ID int,name varchar (20) ; CREATE table employee (ID int primary KEY auto_increment,name varchar (20), sex enum (

I. Summary of MYSQL commands1. Create a librarycreate database test1;2. Authorizing a usergrant all privileges on *.* to ‘feng‘@‘%‘ identified by ‘[email protected]‘;3. Create a tablecreate table Teacher(teaId int not null,teaname varchar(100),age

I. Summary of MYSQL commands1. Create a librarycreate database test1;2. Authorizing a usergrant all privileges on *.* to ‘feng‘@‘%‘ identified by ‘[email protected]‘;3. Create a tablecreate table Teacher(teaId int not null,teaname varchar(100),age

1, sort, add serial number according to total scoreTable structure:Sql:SET @row = 0;SELECT b.*, @row: [Email protected]+1 rownum from (Select *,sum (a.achievement) as Achievementall from CP_CJ as awhere 1=1 GROUP by A.studentnum Order by SUM

Multi-Table Connection query# Focus: External link syntax SELECT Field List From table 1 INNER| Left| Right JOIN table 2 = Table 2. Fields;Cross Connect: No matching criteria are applied. Generate Cartesian productMysql> SELECT * fromemployee,

First, user Rights managementAssigning permissions:Grant permission list on object list to user @localhostReclaim Permissions:Revoke permissions list on object list from user @localhostParameters:Permissions List:

Symptom: Client MySQL cannot link prompt more than max_connections if restarting MySQL or stopping MySQL and restarting the system takes a long time 1 small into the left and right　　Problem descriptionWhen MySQL is installed on the server, an

Mainly from the above space to introduce some of MySQL's knowledge pointsI. MySQL INTRODUCTIONMySQL is a relational database management system developed by the Swedish MySQL AB company and is currently part of Oracle's product portfolio. MySQL is

first, review the following details:Create a test libraryCreate DATABASE test;Authorizing a userGrant all privileges on * * to ' xiang ' @ ' percent ' identified by ' [email protected] ';Create a tableCREATE TABLE student (ID int not

The architecture of the MySQL database is as follows:As you can see, MySQL is mainly divided into the following components: Connection Pool Components Manage services and tools components SQL Interface Components Parser

The main contents of the MySQL index include the type of index commonly used by MySQL (primary key index, unique index, normal index and full-text index and composite index) and two commonly used structure B-tree, hash index (custom hash index and

First, the problem descriptionIn Oracle, PostgreSQL is running the HIBENATE/JPA application, while switching to MySQL while inserting the data times wrong: "Mysqlintegrityconstraintviolationexception:cannot Add or update a child row:a FOREIGN KEY

In general, we enter directly in the terminal:PIP3 Install Pymysqlwill be able to install successfully automatically.But sometimes we have to specify a Python interpreter first:For example we specify Python3 in terminal cmd input: python3 -m pip