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1. The difference between count (1), COUNT (*), and count (column name)Believe that you are always at work, or in the study of Count () in the end how to use faster. There has been a lot of doubt, some people say that count (*) faster, some people

The number of records in the database table is: Sql> Select COUNT (*) from table_name t; COUNT (*)----------6873 1, using the statistical results of COUNT (*): Sql> alter session Set Nls_language = "American"; Session altered. Sql> set timing on;Sql>

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

Execution effect: 1. Count (1) and COUNT (*) when the table has a larger amount of data, using count (1) is more time-consuming than using count (*) when analyzing the table. From the execution plan, the effect of count (1) and COUNT (*) is the

Select count (*), Count (1), and Count (column) In SQL Server, Count (*), Count (1), or Count ([column]) is perhaps the most common aggregate function. Many people cannot tell the difference between the three. This article will explain the functions,

The problem stems from a problem with the python-CN Mail List: http://groups.google.it/group/python-cn/browse_thread/thread/758891b4342eb2d9/92c12bf6acd667ac Interestingly, why is the result of SYS. getrefcount (11111111) in python2.4 2, but

Either count (*) or COUNT (1) or count ([column]) in SQL Server is perhaps the most commonly used aggregate function. Many people actually distinguish between the three. This article will explain the role of these three, relations and the underlying

[PHP source code reading] count function, php source code count function. [PHP source code reading] count function, php source code count function in PHP programming, when traversing the array, it is often necessary to calculate the length of the

[PHP source reading]count function, PHP source Count function In PHP programming, when iterating over an array, it is often necessary to calculate the length of the array as the judgment condition for the end of the loop, and in PHP the operations

Either count (*) or COUNT (1) or count ([column]) in SQL Server is perhaps the most commonly used aggregate function. Many people actually distinguish between the three. This article will explain the role of these three, relations and the underlying