search
HomeBackend DevelopmentPHP Tutorial求大神解答一个数据库语句的问题

SELECT `id` , `time` , `title`FROM `think_infor`WHERE `type` LIKE '$k-%'			UNION ALL			SELECT `id` , `time` , `title`FROM `think_infor2`WHERE `type` LIKE '$k-%'			ORDER BY `time` DESCLIMIT 0,6


用这个语句可以查询到表1和表2的最新6条信息。但是怎么判断记录是哪个表返回的?
或者有什么其他的方法可以实现,不想多次查询


回复讨论(解决方案)

你带上表名不就行了?

不过你能得到 表1和表2的最新6条信息 吗?

SELECT A.id AS aid , A.time AS atime , A.title AS atitle, B.id AS bid , B.time AS btime , B.title AS btitle
FROM think_infor AS A, think_infor2 AS B
WHERE A.type LIKE '$k-%' AND B.type=A.type
ORDER BY A.time DESC LIMIT 0,6

SELECT A.id AS aid , A.time AS atime , A.title AS atitle, B.id AS bid , B.time AS btime , B.title AS btitle
FROM think_infor AS A, think_infor2 AS B
WHERE A.type LIKE '$k-%' AND B.type=A.type
ORDER……


这个差不多,但是A表的记录是会有重复记录

SELECT `id` , `time` , `title`, 1 as cpfromFROM `think_infor`WHERE `type` LIKE '$k-%'			UNION ALL			SELECT `id` , `time` , `title` , 2 as cpfromFROM `think_infor2`WHERE `type` LIKE '$k-%'			ORDER BY `time` DESCLIMIT 0,6

这个语句写的不是很清楚

引用 2 楼 yiwusuo 的回复:SELECT A.id AS aid , A.time AS atime , A.title AS atitle, B.id AS bid , B.time AS btime , B.title AS btitle
FROM think_infor AS A, think_infor2 AS B
WHERE A.type LIKE……
ORDER BY A.time DESC 后面加上:having count(A.id)=1 
不就没重复了吗

我自己都觉得乱了,我还是说一下我想要的东西吧


有A表,B表,结构相同,数据不同,我想同时模糊查询一个字段`type`,选取两表中符合条件的前6条记录(根据`time`排序)

你自己写的不就可以吗?

SELECT `id` , `time` , `title`, 'think_infor' as tbl_name  FROM `think_infor`  WHERE `type` LIKE '$k-%'UNIONSELECT `id` , `time` , `title`, 'think_infor2'   FROM `think_infor2`  WHERE `type` LIKE '$k-%'ORDER BY `time` DESCLIMIT 0,6

加了个输出字段 tbl_name 用以区分数据来源
union all 改成 union 用于避免出现重复记录。不多加了来源就重复的也不重复了

你自己写的不就可以吗?


SQL code
?



123456789

SELECT `id` , `time` , `title`, 'think_infor' as tbl_name   FROM `think_infor`   WHERE `type` LIKE '$k-%'UNIONSELECT `id` , `time` , `title`, 'think_in……

SELECT 不存在的字段这也可以

你是指 'think_infor' as tbl_name 这个吗?

那么你认为 SELECT `id` as iidd  FROM `think_infor` 这样可以吗?
肯定可以了,不就是给个名字么

接下来就不说了

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
Optimize PHP Code: Reducing Memory Usage & Execution TimeOptimize PHP Code: Reducing Memory Usage & Execution TimeMay 10, 2025 am 12:04 AM

TooptimizePHPcodeforreducedmemoryusageandexecutiontime,followthesesteps:1)Usereferencesinsteadofcopyinglargedatastructurestoreducememoryconsumption.2)LeveragePHP'sbuilt-infunctionslikearray_mapforfasterexecution.3)Implementcachingmechanisms,suchasAPC

PHP Email: Step-by-Step Sending GuidePHP Email: Step-by-Step Sending GuideMay 09, 2025 am 12:14 AM

PHPisusedforsendingemailsduetoitsintegrationwithservermailservicesandexternalSMTPproviders,automatingnotificationsandmarketingcampaigns.1)SetupyourPHPenvironmentwithawebserverandPHP,ensuringthemailfunctionisenabled.2)UseabasicscriptwithPHP'smailfunct

How to Send Email via PHP: Examples & CodeHow to Send Email via PHP: Examples & CodeMay 09, 2025 am 12:13 AM

The best way to send emails is to use the PHPMailer library. 1) Using the mail() function is simple but unreliable, which may cause emails to enter spam or cannot be delivered. 2) PHPMailer provides better control and reliability, and supports HTML mail, attachments and SMTP authentication. 3) Make sure SMTP settings are configured correctly and encryption (such as STARTTLS or SSL/TLS) is used to enhance security. 4) For large amounts of emails, consider using a mail queue system to optimize performance.

Advanced PHP Email: Custom Headers & FeaturesAdvanced PHP Email: Custom Headers & FeaturesMay 09, 2025 am 12:13 AM

CustomheadersandadvancedfeaturesinPHPemailenhancefunctionalityandreliability.1)Customheadersaddmetadatafortrackingandcategorization.2)HTMLemailsallowformattingandinteractivity.3)AttachmentscanbesentusinglibrarieslikePHPMailer.4)SMTPauthenticationimpr

Guide to Sending Emails with PHP & SMTPGuide to Sending Emails with PHP & SMTPMay 09, 2025 am 12:06 AM

Sending mail using PHP and SMTP can be achieved through the PHPMailer library. 1) Install and configure PHPMailer, 2) Set SMTP server details, 3) Define the email content, 4) Send emails and handle errors. Use this method to ensure the reliability and security of emails.

What is the best way to send an email using PHP?What is the best way to send an email using PHP?May 08, 2025 am 12:21 AM

ThebestapproachforsendingemailsinPHPisusingthePHPMailerlibraryduetoitsreliability,featurerichness,andeaseofuse.PHPMailersupportsSMTP,providesdetailederrorhandling,allowssendingHTMLandplaintextemails,supportsattachments,andenhancessecurity.Foroptimalu

Best Practices for Dependency Injection in PHPBest Practices for Dependency Injection in PHPMay 08, 2025 am 12:21 AM

The reason for using Dependency Injection (DI) is that it promotes loose coupling, testability, and maintainability of the code. 1) Use constructor to inject dependencies, 2) Avoid using service locators, 3) Use dependency injection containers to manage dependencies, 4) Improve testability through injecting dependencies, 5) Avoid over-injection dependencies, 6) Consider the impact of DI on performance.

PHP performance tuning tips and tricksPHP performance tuning tips and tricksMay 08, 2025 am 12:20 AM

PHPperformancetuningiscrucialbecauseitenhancesspeedandefficiency,whicharevitalforwebapplications.1)CachingwithAPCureducesdatabaseloadandimprovesresponsetimes.2)Optimizingdatabasequeriesbyselectingnecessarycolumnsandusingindexingspeedsupdataretrieval.

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

VSCode Windows 64-bit Download

VSCode Windows 64-bit Download

A free and powerful IDE editor launched by Microsoft

SublimeText3 Linux new version

SublimeText3 Linux new version

SublimeText3 Linux latest version

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Safe Exam Browser

Safe Exam Browser

Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.