MySQL

Yesterday time limit just wrote how to connect the database, the purpose of connecting the database is to query, modify the data, just connected or meaningless.The main method of Statement interface (java.sql.Statement) is used for data crying

Database creation Script:/*navicat mysql data transfersource server          : localhostSource Server Version : 50621Source Host            : localhost:3306Source Database        : cmm-dbtarget server type    : mysqltarget

Installing MySQL on Ubuntu is very simple and requires just a few commands to complete. 1. Sudo apt-get install mysql-server   2. Apt-get Isntall mysql-client  3.sudo apt-get install Libmysqlclient-devDuring installation, you will be prompted to

From:http://www.2cto.com/database/201302/189920.html Mysql:charset and collation settings  charset and collation have multiple levels of settings: server-level, database-level, table-level, column-level, and connection-level    www.2cto.com-

Start by counting all the tables to seeNumber Type Column type The amount of storage needed TINYINT 1 bytes SMALLINT 2 bytes MEDIUMINT 3 bytes INT 4 bytes

InnoDB extends the primary key columns by automatically adding them to each two-level index:CREATE TABLET1 (I1INT not NULL DEFAULT 0, I2INT not NULL DEFAULT 0, D DATEDEFAULT NULL, PRIMARY KEY(I1, i2),INDEXK_d (d)) ENGINE=InnoDB;The table

1, when only one row of data is used with LIMIT 1If you explicitly take only one piece of data, add limit 1;2, Avoid SELECT *, get fields as neededYou should develop a good habit of taking whatever you need.3, use ENUM instead of VARCHARThe ENUM

MySQL supports foreign key storage engine only InnoDB, when creating foreign keys, requires the parent table must have a corresponding index, the child table when creating foreign keys will also automatically create the corresponding index. When you

Transfer from http://www.cnblogs.com/wangtao_20/archive/2011/02/24/1964276.htmlWhat is the rationale for using the view? 1. Security. This is typically done by creating a view that defines the data that the view operates on. The user rights are then

This section discusses the optimization of the WHERE clause, not only in select, the same optimizations are also tried with the WHERE clause in the DELETE and UPDATE statements;1: Remove unnecessary parentheses: and and OR and and and d )))) -

Amoeba is a proxy that uses MySQL as the underlying data store and provides the MySQL protocol interface to the application. It responds centrally to the application's requests, sending SQL requests to a specific database based on the rules that the

1. Set or modify the MySQL root password:Default post-installation blank password, set password with mysqladmin command:Mysqladmin-uroot Password "password"MySQL command set Password:mysql> Set password for [email protected]=password (' password

To Create a database :Create DATABASE [if not exits] DB name [database option];DescriptionDatabase name: can be any character, but special characters need to use anti-quote wrapping, the size of the identifier is used to distinguish the operating

vi/usr/local/killmysqlprocess.sh#!/bin/bash#*/1 * * * */usr/local/src/killmysqlprocess.shbackdir= "/usr/local/logs/" logfile= "Cms_mysql_killprocess_ $ (date + "%y%m%d"). Log "mysqlbindir="/usr/local/mysql/bin/"#use commond ' Vmstat ' get proc

--jfinal error hint Duplicate entry ' 1791361-1823391 ' for key ' PRIMARY '--1. View the primary key generator values for SSDBSsdb 127.0.0.1:8888> Scan t_resource_base t_resource_basezzzz 100Key value-------------------------t_resource_base_pk:182339

Tutorial on using CONCAT functions in MySQL This article describes how to use the CONCAT function in MySQL. It is the basic knowledge of getting started with Python. For more information, see Use the MySQL CONCAT () function to connect two strings

Yahoo open-source MySQL Performance Analysis Tool (MySQL Performance Analyzer)MySQL Performance Analyzer is an open source project for MySQL performance monitoring and analysis. This repository implements des two sub projects: Java web application

Mysql deadlock caused by full disk Today, I encountered a problem because the disk of the machine where mysql is located is full, leading to a mysql deadlock and not even querying the select statement. If I did not read the mysql Log, I could not

The use of indexes in MySQL and the SQL types that actually use Indexes 1. Why are indexes used?Without an index, MySQL scans the entire table to find records that meet the SQL conditions. The time overhead is positively related to the data volume

WITHROLLUP in MySQL MySQL's extended SQL has a very interesting application WITH ROLLUP. The same statistics (SUM, AVG, COUNT…) are performed based on the grouping statistics ...), Similar to the statistical functions in Oracle, Oracle's statistical