MySQL

When the database query rate is slow, the corresponding table can be added to the corresponding index, which can effectively improve the query efficiency, the MySQL database added indexed SQL into the following:ALTER TABLE ' table_name ' ADD INDEX

the principle of MySQL master (Master) copy from (slave) :1. Master records data changes to binary logs (binary log ) , which is the configuration file log-bin Specified files ( These are called binary log events, binary logs event)2. Slave

Immediately following the previous chapter, because the project is now based on spring as the main container management framework, write how spring integrates multiple data sources.1.backgroundwe generally apply to the database is "read more write

Determine two servers MySQL version consistent 1. Modify master server Master configuration # Edit Profile vi/etc/my.cnf [mysqld] Log-bin=mysql-bin//[must] enable binary log, add log directory Server-id=7// [must] from the server unique ID, the

The modified users are listed as root.first, the root of the original myql password;Method One:Outside the MySQL system, use the Mysqladmin#mysqladmin-u root-p Password "test123"Enter Password: "Enter the original password"Method Two:By logging into

Implement a simple move table, using a cursor loopThe first line DELIMITER//and the last line//must, or encounter a semicolon to errorDelimiter //create procedure movedata () begin      declare  Done int default 0;           declare  v_id varchar (+)

paging operation: Starting position with limit (parameter 1, parameter 2) (parameter 1)=(Page No.-1)*number of bars displayed per page (parameter 2)1. Classification TableCreate TableCategory (CIDvarchar( +)Primary Key, CNAMEvarchar( -));2.

Design Optimization – scenarios where the index cannot be used? the number of records scanned by the index exceeds 30% and becomes a full table scan? in a federated index, the first index column uses a range query--only partial indexes are used? in

1. Create Group Byselect ven_id,count (*) as Num_prods from the products group by VEN_ID; Note: Group by can contain any number of columns each column listed by the group must be retrieved A column or a valid expression (but not a clustered function)

How to use exists and in:SELECT * from a where exists (select * from B where a.id=b.id), select * from a where a.id in (select ID from B);1, exists is to do Loop loop, each loop loop and then query the internal table (sub-query), then is the index

Create a library operationHttp://www.cnblogs.com/linhaifeng/articles/7211690.html---------------------------------1, create database homework; Create DATABASE)2, show create database homework; Query creation Process3, drop database homework;

Operations on Table RecordsHttp://www.cnblogs.com/linhaifeng/articles/7267587.htmlAdd: Insert1. Insert full data (sequential insertion)Syntax One:INSERT into table name (Field 1, Field 2, Field 3 ...) field N) VALUES (value 1, value 2, value 3 ...)

Brief introductionConfigure MySQL etc under my.conf configuration details as follows[Client]Port = 3306Socket =/tmp/mysql.sockDefault-character-set = Utf8mb4[MySQL]prompt= "MySQL [\d]>"No-auto-rehash[Mysqld]Port = 3306Socket =/tmp/mysql.sockBasedir =

　　1, download MySQLOpen MySQL's official website www.mysql.com, found a downloadsClick on it, go to the MySQL download page, there is a MySQL Community Edition at the bottom of the page, and there is a blue link belowClick on this blue link to go to

First, the data type See: http://www.runoob.com/mysql/mysql-data-types.html Ii. Types of choice Plastic >date,time>enum,char>varchar>blob,text For data types of the same level, it is preferable to select a data type that occupies

"java" import="java.sql.*" contenttype= "Text/html;charset=utf-8"%> String path = Request.getcontextpath (); String basepath = request.getscheme () +"://" +request.getservername () +":" +request.getserverport () +path+   "/"; %> "-//W3C/

One, MySQL server logical architecture diagram      each dashed box is a layer: the first layer: the topmost server is not unique to MySQL, most network-based client/server tools or services have similar systems. such as link processing,

SQL Server and MySQL have some differences in the concurrent processing of "yes, update, no ., Sqlmysql   "Update if yes, insert logic if no exist" concurrent processing In sqlserver: In sqlserver, you can lock a range by serializing the isolation

Mysql -- view,1. view features When a view comes from multiple basic tables, data cannot be added or deleted.2. Create a view Although a view can be viewed as a virtual table, it does not physically exist, that is, the database management system

MySQL-basic concepts, I. Mysql logic architecture Reference from high performance Mysql Ii. Concurrency Control Read/write locks: Read locks are shared and exclusive, blocking other write and read locks. Lock granularity: Table lock and