MySQL

00–undo LogUndo log is for the atomicity of transactions, in the MySQL database InnoDB storage engine, also with the undo log to achieve multi-version concurrency control (abbreviation: MVCC). -Atomicity of the transaction (atomicity)All operations

A transaction is a series of steps for a logical unit of work.Transactions are used to ensure the security of data operations characteristics of a transaction : atomicity ( Atomic Nature ) Consistency ( stability , consistency ) Isolation (

Database1. Query the size of all data: data_length: Data size index_length: Index sizeSELECT concat (Round (sum (data_length+index_length)/1024/1024,2), ' MB ') as DATA from INFORMATION_SCHEMA. Tables\g2. View the size of the specified database,

First, mathematical functionsMathematical functions are mainly used for processing numbers, including integers, floating-point numbers, and so on.ABS (x)Returns the absolute value of XSELECT ABS (-1)--return 1Ceil (x), CEILING (x)Returns the

The following is the entire process of creating a write to delete, to a drop:1: Create a databaseCreate Database it1110;2: Enter this databaseUse it1110;3: Create a data tableCreate Table Teac (Id int,Name varchar (30));4: Write InformationInsert

When you use. NET connector to connect to the MySQL database and retrieve some data, you may get an error message:"Unable to convert MySQL date/time value to System.DateTime"This is because there are "0000-00-00" data values in the Date column to

/** Creating a database **/Create Database testdata;/**return to query OK; Indicates that the creation was successful.**//** Deleting a database **/Drop database testdata;/**return to query OK; Indicates a successful creation**//** shows the engines

For MyISAM types of tables, you can quickly import large amounts of data in the following ways:ALTER TABLE tblname DISABLE KEYS;Loading the dataALTER TABLE tblname ENABLE KEYS;These two commands are used to open or close an update for a non-unique

Let's talk about MySQL. When compiling the installation, the options for the character set (http://coosh.blog.51cto.com/6334375/1735271)Specify the default character set for the database-ddefault_charset=utf8Specify the default proofing character

This article mainly introduces the single server MySQL database multiple instances of the master-slave synchronization, general general master from the replication slave server on different machines, and listening ports are the default 3306 port.I.

# Configuration environment: Windows 64bit# Installed version: Mysql-5.7.10-win32 (Zip archive version)1. ZIP version Archive is free to install, simply unzip the mysql-5.7.10-win32.zip to the installation directory.2. Under the D:\Program

Get user nickname nickname with emoji expression, converted to character code is this form "\xf0\x9f\x91\x8d\xe6\x94 ...",The following error may occur with direct savecaused By:java.sql.SQLException:Incorrect string value: ' \xf0\x9f\x98\x84 '

The test script is as follows:1 CREATE TABLE test12 (3 ID int primary KEY auto_increment,4 name varchar (20) 5);Test code:1 package Me.gacl.demo; 2 3 import java.sql.Connection; 4 import java.sql.PreparedStatement; 5 import

Let's start with a little digression, LZ learning Java Web recently.Today, I just saw hibernate, hair now hibernate configuration data source when the online information is too long, generally with the Tomcat 5 version of the configuration of the

1. Preparatory work:Yum install gcc gcc-c++ ncurses-devel perlAfter mysql5.5, the source installation needs CMakewget http://www.cmake.org/files/v2.8/cmake-2.8.10.2.tar.gzTAR-XZVF cmake-2.8.10.2.tar.gzCD cmake-2.8.10.2./bootstrap; make; Make

With regard to the benefits of MySQL indexing, if the correct design and use of the indexed MySQL is a Lamborghini, then no design and use of the index of MySQL is a human tricycle. For tables that do not have an index, a single-table query might be

Sometimes forget the root password of MySQL, in this case, how to reset the root password?Locate and edit the MySQL my.ini configuration file and add the skip-grant-table to the MYSQLD node as follows:[Mysqld]# These let you safely reset the lost

Modify the MySQL configuration file my.cnf, the path is/ETC/MY.CNF Write a line skip-grant-tables in the configuration file, save and exit after adding, as650) this.width=650; "src=" Http://s4.51cto.com/wyfs02/M01/79/74/wKioL1aR-HfzDOxdAAAZwP_l6kQ1

MySQL counters, such as the number of site hits, how to achieve high-performance concurrency counter function clicks:5338Date: the-Geneva- in at: -: thePower by Li Xuan lanetagmysql counter High performance now there are a lot of projects, the

Install mysql5.6 today, as soon as this step to report the following error. Originally tried to add the-fpic parameter, but did not know where to go 650) this.width=650; "title=" Image () "style=" border-top:0px; border-right:0px; border-bottom:0px;