mysql count with condition

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Usage differences for COUNT (ID) count (1) count (*) in MySQL

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

In MySQL, COUNT (1) is compared to count (*)

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 difference between count (Primary_key), COUNT (1), COUNT (*) in MySQL

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 '

Several ways to count MySQL by condition

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 interpretation

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,

Optimization of innodb table count () in mysql

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

MySQL database Optimization-COUNT (*) Efficiency

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

With Count (*) or count (column name) | | Count () differs from sum () in MySQL

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

Learn MySQL (UP)

Concrete Example 1. PHP Server ComponentsFor beginners, it is recommended to use the integrated server component, which already includes PHP, Apache, Mysql and other services, eliminating the time spent by developers in the tedious configuration

Mysql Optimization-COUNT (*) Efficiency Analysis

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

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