mysql top n per group

Alibabacloud.com offers a wide variety of articles about mysql top n per group, easily find your mysql top n per group information here online.

MySQL Top n per group

SELECT * from (Select Case whenT.province=@prov Then @rownum:=@rownum+1 Else @rownum:=1 EndRowNum, Case whenT.province=@prov Then 0 Else @prov:=T.provinceEndProv, T.* from ( SELECT '110000'Province,1231 Money UNION All SELECT '11

SQL Group One (or several) records per group (rank)

MySQL Group takes the first few records of each group (rank) with group by and order byHttp://www.jb51.net/article/31590.htm--group The data of the row with the maximum (small) value by a fieldThe code is as follows:/**/--Create the table and insert

MySQL takes the first n records of each group

First, the record of the group to take the top N records: Example: Take the first 2 maximum (small) records1 1. Using subqueries:2SELECT * from Right2 a WHERE2>3(SELECT COUNT (*) from right2 b WHERE b.id=a.id and b.account>a.account)4 ORDER by

How to select the first row/last row/top row of each group in SQL

Reprint Please specify: theviper http://www.cnblogs.com/TheViperPartially translated from How to select the First/least/max row per group in SQLSome common SQL problems have similar workarounds, such as finding the most recent logs for each program,

Years of O & M experience, details on how to optimize MySQL data

The database design may only be based on the current business needs. It may not need high availability, high scaling, and other features at that time, but as the business and user volume increase, the infrastructure is gradually improved. This blog

Word summary: Learn MySQL optimization principle (GO)

This article transferred from: HTTPS://WWW.TUICOOL.COM/WX/2EMBFMQObjectiveTalking about MySQL query optimization, I believe you have a collection of artifice: You cannot use SELECT *, do not use null fields, reasonably create an index, select the

MySQL group query before n data

Build table:CREATE TABLE Hard (ID INT,AA varchar (50),BB INT,PRIMARY Key (ID))INSERT into hard values (1, ' a ', 9)INSERT into hard values (2, ' a ', 7)INSERT into hard values (3, ' a ', 8)INSERT into hard values (4, ' a ', 6)INSERT into hard values

MySQL group query before n data

Build table:CREATE TABLE Hard (ID INT,AA varchar (50),BB INT,PRIMARY Key (ID))INSERT into hard values (1, ' a ', 9)INSERT into hard values (2, ' a ', 7)INSERT into hard values (3, ' a ', 8)INSERT into hard values (4, ' a ', 6)INSERT into hard values

Centos6.4 platform Installation MySQL

Platform: centos6.4 Mysql:mysql-5.5.33-linux2.6-x86_64.tar.gz One, build LVM, and prepare before installation: #查看当前磁盘的分区 (here alone with a new plus disk for LVM) [Email protected] ~]# fdisk-l/dev/sdbdisk/dev/sdb:128.8 GB, 128849018880 bytes255

MySQL database optimization technology configuration and indexing (mandatory)

(1) Reduce Database Access Static pages are possible Static parts of a dynamic page Some data can be generated as XML or saved as text files Use data caching technology, such as memcached (2)Optimization Detection Method 1. User Experience

Total Pages: 9 1 2 3 4 5 .... 9 Go to: Go

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

  • Sales Support

    1 on 1 presale consultation

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.