MySQL

Innodb_flush_log_at_trx_commit and Sync_binlog two parameters are key parameters for controlling MySQL disk write policy and data security.If Innodb_flush_log_at_trx_commit is set to 0,log buffer, it is written to log file once per second, and the

#mysql批量修改字段类型 # Gets the modification statement and stores the use DB to the temporary table; CREATE temporary table Xiugai SELECT CONCAT ( ' alter TABLE ', TABLE_NAME, ' MODIFY COLUMN ', column_name, ' new type D ' Efault NULL; ' ) As Col

(1). First Class:Create View as Select * from table;(2). Type II:Create View as Select from table;(3). Category III:Create View v[vid,vname,vage]asselectfromtable ;If the amount of data involved is too large, the business logic needs a

Http://www.cnblogs.com/zl0372/articles/mysql_32.htmlSo there is a table:CREATE TABLE ' User_group ' ( ' id ' int (one) not null auto_increment, ' uid ' int (one) ' NOT null, ' group_id ' int (one) N OT NULL, PRIMARY key (' id '), key '

Substring_index (Str,delim,count)STR: The string to be processedDelim: DelimiterCount: CountExample: str=www.baidu.comSubstring_index (str, '. ', 1)The result is: wwwSubstring_index (str, '. ', 2)The result is: Www.baiduThat is, if Count is a

ConstraintsWhat is constraint?constraint is a "provision" that requires data to meet what conditions .There are several constraints:PRIMARY KEY constraint: form: primary key ( field name );meaning (function): The value of the setting field can be

Discrete Query SELECT * from car where price=30 or price=40 or price=50 or price=60; SELECT * from car where price in (30,40,50,60) takes out the data Select * from car where price is not in (30,40,50,60) removes data Aggregate function (System

Objective:MySQL partition after each partition into a separate file, although logically or a table actually has been divided into a number of separate tables,From INFORMATION_SCHEMA. Innodb_sys_tables system table can see that each partition has a

Foreword: Prior to testing the SOLR several versions were unsuccessful, SOLR is better to download version 5.0,5.5,6.6. solr6.6 combined with TOMCAT8 to do automatic synchronization MySQL data has been error, and then decisively test 5.5 version of

(store) function:function, also referred to as "storage function", is actually JS or php in the said function! The only difference:the function here must return a data (value);definition form:Precautions:1, within the function, can have a variety of

1. System RequirementsMount/dev/cdrom/mntYum install-y Cmake,make,gcc,gcc-c++,bison, Ncurses,ncurses-devel2. Create users and GroupsGroupadd MySQLuseradd-g MySQL MySQL3. Create a Database installation directoryMkdir/mysql/mysql/data/mysql/logChown-r

Basic Operations View Help(help?) \h \?Exit (Exit Quit)\qIf you write the wrong command, you want to clear the statement of the current input command, and then add (clear) after the wrong command.\cClear ScreenClsDatabase operations increase the

The table structure is as follows650) this.width=650; "src=" Https://s1.51cto.com/wyfs02/M02/9E/42/wKioL1mOl66xQ0a1AAA6Sw4G6jw633.png "title=" 1.png "alt=" Wkiol1mol66xq0a1aaa6sw4g6jw633.png "/>The requirements name and password fields, which

1. Install the required packages for the compiled code:Yum List|grep ncurses-develyum-y Install make gcc-c++ cmake bison-devel ncurses-devel 2. Download MySQL 5.6.35wget https://cdn.mysql.com//Downloads/MySQL-5.6/mysql-5.6.35.tar.gzTar zxvf mysql-5.6

A partitioned table is a separate logical table for the user, but the bottom layer consists of multiple physical sub-tables. The code that implements the partition is actually the encapsulation of the handle object of a set of underlying

1. Download binary filesDownload mysql-5.6.36-linux-glibc2.5-i686.tar.gz on the http://dev.mysql.com/downloads/mysql/official website.2. Unzip the file and move it to the/usr/local/mysql directoryTAR-ZXVF mysql-5.6.36-linux-glibc2.5-i686.tar.gz3.

Mysql version upgradeCurrent version: 5.7.18Upgraded version: 5.7.191. Copy the new version to the specified directory.[Root @ izwz9gxsbwybwg9n5xdi47z soft] # cp mysql-5.7.19-linux-glibc2.12-x86_64.tar.gz/opt/2. Extract[Root @

MySQL optimization in the production environment and mysql optimization in the environment A: hardware optimization: 1. Use a 64-bit cpu with at least 4 CPUs. The larger the L2 cache, the better.2. Large Memory, 1-2 instances running 32-64 GB, and 3-

Extreme storage-historical linked list (top) and zipper In the data model design process of the data warehouse, we often encounter the following requirements: 1. Large data volume;2. Some fields in the table will be updated, such as the user's

Java_JDBC _ use the method of reading the configuration file to connect to the database, java_jdbc configuration file 1 package com. homewoek3_4.dao; 2 3 import java. io. IOException; 4 import java. io. inputStream; 5 import java. SQL. connection; 6