MySQL

Distinct can remove duplicate lines, query time with SELECT DISTINCT * from ...;Unique is one of the integrity constraints in MySQL and adds a unique constraint if the value of a column needs to be unique.The purpose of creating a unique index is

Force index forced Indexesuse only the indexes that are built on field1 , not the indexes on other fields. SELECT * FROM table1 Force INDEX (field1)IGNORE Index ignores indexesIndexes on Field1 and field2 in table1 tables are not usedSELECT * FROM

One, MySQL connection number1. Configure MySQL Connection number:VIM/ETC/MY.CNF [mysqld] modified belowmax_connections=1000 does not write default to 100.Wait_timeout=60 setting the time-out period2. View the current number of connections:Show

Mysql> Pager MorePAGER set to ' more 'Mysql> Pager LessPAGER set to ' less 'Mysql> NopagerPAGER set to stdoutThree states of MySQL pagerSet upMysql> Pager MorePAGER set to ' more 'Then the query, our results will not be a real flash, will only show

Today the company has a MySQL share, do a record, perhaps a lot of things very simple, but it is difficult for people who do not know1. Store with minimal costFor example, if you can determine that a field is stored in numbers, and the number must

Exceptions encountered by Web development:Com.mysql.jdbc.CommunicationsException:The last packet successfully received from the server was58129 seconds ago. Thelast Packet sent successfully to the server was 58129 seconds ago, which islonger than

MySQL has 2 different places from windows1, My.ini Save to/etc/my.ini2, user rights, individual user executionOne: Download: direct command download.wget Http://mirrors.sohu.com/mysql/MySQL-5.7/mysql-5.7.17-linux-glibc2.5-x86_64.tarSecond, the

1, the environment is centos6.5 32-bit system, Python version is 2.7.12,mysql version is 5.5.22. Prepare the required compression pack, mysql-python-1.2.4b4.tar.gz pip-6.0.7.tar.gz setuptools-12.0.32, using Python to operate MySQL first need to

The reason for writing this article is: In the beginning to use the Linux operating system to build the lamp environment, and began to search for information on Google and Baidu, met not a lot of problems, I decided to write this article summed up

MySQL Sub-Library sub-table scheme Why do you want to divide tablesWhen the data of a table reaches tens of millions of, the time you spend querying is much more, and if you have a joint query, I think I might die there. The purpose of the sub-table

First, the MySQL connection local database, the user name "root", the password "123456": d:\>mysql-h localhost-u root-p123456 Note: "-P" and "123456" can not have space between two, MySQL Connect the data specified in the local database, the

Under Window1. Export the entire database- - > Mysmart_anju.sql2. Export a table- - Floor > Mysmart_anju_floor.sql3. Export a database structure- - - -- add-drop-table Smart_anju > Mysmart_anju_str.sql-D No data--add-drop-table add a drop table

If the. sql file is too large, MySQL will disconnect directlyWorkaround:Add a line Max_allowed_packet = 100M (the size >=mysql.sql file size) in the MySQL configuration file

Install mysql on linux and use it easily. 1. Install mysql Sudo apt-get update Sudo apt-get install mysql-server Sudo apt-get install python-mysqldb (if you want to use it in python, install it) 2. log on to the root user: Mysql-u root-p 3. view all

Mysql limit paging usage and points of attention, mysqllimit Usage and precautions of mysql limit paging: When we use a query statement, we often need to return the first few or a few rows of data in the middle. What should we do at this time? Don'

MySQL5.7 new group by feature error 1055 solution, mysql5.71055 The project was originally developed using mysql5.6. After switching to 5.7, it suddenly found that some of the original SQL statements run with an error code of 1055. The error message

Mysql storage engine details Introduction to the storage engine A relational database table is a data structure used to store and organize information. It can be understood as a table composed of rows and columns.Because of the different types of

A Brief Introduction to MySQL5.7 JSON format retrieval, mysql5.7json MySQL and later versions support JSON format. When creating a table, you can specify the Data Type of the List as JSON. But how to create an index in JSON format ?? I did a simple

Innodb table select query order, innodbselect Query Today, a student from zhishutang reported that in the optimization class, the teacher told me that Innodb is stored in the primary key order, and the read time is read in the primary key order.

Common SQL statements and SQL statementsCreate a table: create table course( id INT auto_increment, title TEXT NOT NULL, period INT, description TEXT, primary key(id)) ENGINE=INNODB CHARSET=utf8;Insert data to a table in three ways ):