生手关于mysql_num_rows的一个疑问 -PHP Tutorial-php.cn

Home

Backend Development

PHP Tutorial

生手关于mysql_num_rows的一个疑问

WBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWB

Jun 13, 2016 pm 01:14 PM

mysqlqueryselect

新手关于mysql_num_rows的一个疑问。
本人新手，要做一个分页，但是分布功能需要直到表中的数据具体有多少条，所以每次翻页后都需要用到
mysql_num_rows(mysql_query('SELECT * FROM XX));

现在我有个疑问，mysql的mysql_num_rows要取得总记录数是否需要每次都要把表读一遍后才返回结果，还是mysql本身有优化过直接知道总数？

因为记录数比较多，如果此方法太消耗资源，是否有别的方法可以代替？

求高人解答下本人的疑问。 - -

------解决方案--------------------
为什么不用
$resutl = mysql_query("select count(*) from table");
$row = mysql_fetch_array($result);
$row[0];//总行数

Statement

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Dependency Injection in PHP: Avoiding Common PitfallsMay 16, 2025 am 12:17 AM

DependencyInjection(DI)inPHPenhancescodeflexibilityandtestabilitybydecouplingdependencycreationfromusage.ToimplementDIeffectively:1)UseDIcontainersjudiciouslytoavoidover-engineering.2)Avoidconstructoroverloadbylimitingdependenciestothreeorfour.3)Adhe

How to Speed Up Your PHP Website: Performance TuningMay 16, 2025 am 12:12 AM

ToimproveyourPHPwebsite'sperformance,usethesestrategies:1)ImplementopcodecachingwithOPcachetospeedupscriptinterpretation.2)Optimizedatabasequeriesbyselectingonlynecessaryfields.3)UsecachingsystemslikeRedisorMemcachedtoreducedatabaseload.4)Applyasynch

Sending Mass Emails with PHP: Is it Possible?May 16, 2025 am 12:10 AM

Yes,itispossibletosendmassemailswithPHP.1)UselibrarieslikePHPMailerorSwiftMailerforefficientemailsending.2)Implementdelaysbetweenemailstoavoidspamflags.3)Personalizeemailsusingdynamiccontenttoimproveengagement.4)UsequeuesystemslikeRabbitMQorRedisforb

What is the purpose of Dependency Injection in PHP?May 16, 2025 am 12:10 AM

DependencyInjection(DI)inPHPisadesignpatternthatachievesInversionofControl(IoC)byallowingdependenciestobeinjectedintoclasses,enhancingmodularity,testability,andflexibility.DIdecouplesclassesfromspecificimplementations,makingcodemoremanageableandadapt

How to send an email using PHP?May 16, 2025 am 12:03 AM

The best ways to send emails using PHP include: 1. Use PHP's mail() function to basic sending; 2. Use PHPMailer library to send more complex HTML mail; 3. Use transactional mail services such as SendGrid to improve reliability and analysis capabilities. With these methods, you can ensure that emails not only reach the inbox, but also attract recipients.

How to calculate the total number of elements in a PHP multidimensional array?May 15, 2025 pm 09:00 PM

Calculating the total number of elements in a PHP multidimensional array can be done using recursive or iterative methods. 1. The recursive method counts by traversing the array and recursively processing nested arrays. 2. The iterative method uses the stack to simulate recursion to avoid depth problems. 3. The array_walk_recursive function can also be implemented, but it requires manual counting.

What are the characteristics of do-while loops in PHP?May 15, 2025 pm 08:57 PM

In PHP, the characteristic of a do-while loop is to ensure that the loop body is executed at least once, and then decide whether to continue the loop based on the conditions. 1) It executes the loop body before conditional checking, suitable for scenarios where operations need to be performed at least once, such as user input verification and menu systems. 2) However, the syntax of the do-while loop can cause confusion among newbies and may add unnecessary performance overhead.

How to hash strings in PHP?May 15, 2025 pm 08:54 PM

Efficient hashing strings in PHP can use the following methods: 1. Use the md5 function for fast hashing, but is not suitable for password storage. 2. Use the sha256 function to improve security. 3. Use the password_hash function to process passwords to provide the highest security and convenience.

See all articles