mysql count with condition

The table structure is as follows: The code is as follows Copy Code Mysql> Show CREATE TABLE Userg;1. Row ***************************Table:userCreate table:create Table ' user ' (' ID ' int (a) unsigned not NULL

SQL tuning is primarily about reducing the number of consistent gets and physical reads. COUNT (1) is compared with COUNT (*): If your datasheet does not have a primary key, then count (1) is faster than COUNT (*)If you have a primary key, the

The table structure is as follows:Mysql> Show CREATE TABLE user\g;*************************** 1. Row *************************** table:usercreate table:create Table ' user ' ( ' id ' int (ten) unsigned not NULL AUTO _increment, ' name '

Recently, in the background of a website to add a series of statistical functions, encountered a lot of conditions to be counted by the condition. Try several methods, the following summary records, for your reference.Problem descriptionTo make the

MYSQL5.6.7-RC index condition pushdown indexed condition Push code interpretationHttp://jishu.zol.com.cn/4505.htmlMYSQL5.6.7-RC Index Condition pushdown code interpretation a-a+2013-08-07 11:10|Share to:Interested in the index condition Pushdown,

Translator: ye Jinrong (imysql # imysql.com), source: imysql.com, please reprint it. Cause: It is too slow to make count (*) Statistics on the innodb table, so try to see if you can hurry up. Symptom: Let's take a look at several test cases. 1. Test

The performance of the MySQL database is always the focus of discussion. The following describes the efficiency of the COUNT (*) in MySQL database optimization. I hope it will help you. In MySQL database optimization, COUNT (*) and COUNT (COL ):I

Count () differs from sum () in MySQLFirst, create a table to illustrate the problem create table ' result ' (' name ' varchar () default NULL, ' subject ' varchar () default NULL, ' Score ' tinyint ( 4) Default NULL) Engine=myisam default

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I just solved the Discuz he wrote for a friend! Plug-in problems, when talking about the efficiency of MySQL COUNT (*), the more I find it unclear, simply write it down and share it with you. I just solved the Discuz he wrote for a friend! Plug-in