mysql count rows in table

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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

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 '

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

MySQL MyISAM index, INNODB index, count performance analysis Personal Insights

Tested under MySQL 5.6.MyISAM Engine:When creating a data table, MySQL generates 3 files, respectively (table: Test):TEST.FRM, Test. MYD, Test. Myi file,TEST.FRM is the table structure, Test.myd is the file that holds the data, Test.myi is the file

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 Lock table detailed

In order to better optimize MySQL in high concurrency, it is necessary to understand the locking table mechanism when MySQL query is updated.I. OverviewMySQL has three levels of Lock: page level, table level, row level.MyISAM and MemoryStorageThe

Two methods to count the number of rows in the Mysql database

Some time ago, Era shared with you a Mysql database repeat detection function. For how to use this function, you can move to "Repeat detection function when mqsql data is stored in the database-php". today we will introduce two methods to count the

For details about how to use the count function in MySQL, mysqlcount

For details about how to use the count function in MySQL, mysqlcount The count function is a function used to count records in tables or arrays. Here we will introduce the usage and Performance Comparison of the count function in MySQL. Count (*)

Usage of the count function in MySQL

Usage of the count function in MySQL The count function is a function used to count records in tables or arrays. Here we will introduce the usage and Performance Comparison of the count function in MySQL. Count (*) returns the number of rows to be

Time Test for querying the number of data records in MySQL

I. User table information     Ii. Conclusion   Use the query statement: Select count (1) from user; Use the explain statement to check whether the statement is indexed. the following result shows the query time of the statement. Data Volume query

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