问一个联合查询的语句
如上图所示数据表
怎么读出A中的数据呢?(同时也要读出B中对应的数据)
回复讨论(解决方案)
select * from `a` ,`b` where `a`.`bid` like concat('%',`b`.`bid`,'%')
如果要查a表id等于1对应的关联数据,可以写成
select * from `a` ,`b` where `a`.`id`='1' and `a`.`bid` like concat('%',`b`.`bid`,'%')
是要查a表,结果应该类似这样:
Object{ [id] => 1 [bid] => Object { [1] => Object { id => 1 content => 'BBBBB' } [2] => Object { id => 5 content => 'BBBBB' } [3] => Object { id => 2 content => 'BBBBB' } } conent => 'AAAAA'}
类似的php伪代码应该是:
foreach ($tablea->result as $a){ echo $a->id foreach ($a->bid as $b) { echo $b.id; echo $b.content; } echo $a.conent}
打印结果是:
id bid(& b.content) content
------------------------------------
1 1, BBBBBBB AAAAAAAA
1 5, BBBBBBB AAAAAAAA
1 2, BBBBBBB AAAAAAAA
2 2, BBBBBBB AAAAAAAA
2 4, BBBBBBB AAAAAAAA
你要做成这种结果,用程序很容易实现的,上面的SQL其实一定上现实了你的功能
select * from `a` ,`b` where `a`.`bid` like concat('%',`b`.`bid`,'%')
如果要查a表id等于1对应的关联数据,可以写成
select * from `a` ,`b` where `a`.`id`='1' and `a`.`bid` like concat('%',`b`.`bid`,'%')
这是是不是先读b表中的id,然后再模糊查询a表中的bid?
select * from `a` ,`b` where `a`.`bid` like concat('%',`b`.`bid`,'%')
恩,先关联AB表,然后模糊查询a表中的bid是不是在a表的bid中
这样会根据b表的id递增的顺序排序
而不是原先a表中bid逗号字符串的顺序:1,5,2??应该是1-5-2的顺序
建议贴出以下语句以便人家测试
create table ....;
insert into table.... ; 语句
select a.id, b.id as bid, a.content, b.content as bcontent from A表 a, B表 b where find_in_set(b.id, a.bid) order by a.id
select a.id, b.id as bid, a.content, b.content as bcontent from A表 a, B表 b where find_in_set(b.id, a.bid) order by a.id
谢谢版主!
find_in_set(b.id, a.bid)好像只能查询到第一条,比如上面的数据表中a.bid是1,5,2,结果只显示b.id=1的那一条!b.id=5, b.id=2的那几条都没查询出来!
你在表B加个冗余字段A_id多好。
CREATE TEMPORARY TABLE a (id int, bid varchar(10), content varchar(10));INSERT INTO a VALUES('1','1,5,2','AAAAAAA');INSERT INTO a VALUES('2','2,4','AAAAAAA');INSERT INTO a VALUES('3','1,3,2','AAAAAAA');CREATE TEMPORARY TABLE b (bid int, content varchar(10));INSERT INTO b VALUES('1','BBBBB');INSERT INTO b VALUES('2','BBBBB');INSERT INTO b VALUES('3','BBBBB');INSERT INTO b VALUES('4','BBBBB');INSERT INTO b VALUES('5','BBBBB');select a.id, b.bid as bid, a.content, b.content as bcontent from a, b where find_in_set(b.bid, a.bid) order by a.id
原来是我的“1, 5, 2”逗号后面有空格!就没法全查询出来了!空格去掉就ok了
另外,这个find_in_set的查询结果没法按照1-5-2的原始顺序排列!只能按1-2-5递增或5-2-1递减的次序排列啊?
唠叨老大用了另一种更有效率的写法,不过我那些其实也可以得出一样的结果的!
select * from `a` ,`b` where `a`.`bid` like concat('%',`b`.`bid`,'%') order by id

Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics

Long URLs, often cluttered with keywords and tracking parameters, can deter visitors. A URL shortening script offers a solution, creating concise links ideal for social media and other platforms. These scripts are valuable for individual websites a

Laravel simplifies handling temporary session data using its intuitive flash methods. This is perfect for displaying brief messages, alerts, or notifications within your application. Data persists only for the subsequent request by default: $request-

This is the second and final part of the series on building a React application with a Laravel back-end. In the first part of the series, we created a RESTful API using Laravel for a basic product-listing application. In this tutorial, we will be dev

Laravel provides concise HTTP response simulation syntax, simplifying HTTP interaction testing. This approach significantly reduces code redundancy while making your test simulation more intuitive. The basic implementation provides a variety of response type shortcuts: use Illuminate\Support\Facades\Http; Http::fake([ 'google.com' => 'Hello World', 'github.com' => ['foo' => 'bar'], 'forge.laravel.com' =>

The PHP Client URL (cURL) extension is a powerful tool for developers, enabling seamless interaction with remote servers and REST APIs. By leveraging libcurl, a well-respected multi-protocol file transfer library, PHP cURL facilitates efficient execution of various network protocols, including HTTP, HTTPS, and FTP. This extension offers granular control over HTTP requests, supports multiple concurrent operations, and provides built-in security features.

Do you want to provide real-time, instant solutions to your customers' most pressing problems? Live chat lets you have real-time conversations with customers and resolve their problems instantly. It allows you to provide faster service to your custom

The 2025 PHP Landscape Survey investigates current PHP development trends. It explores framework usage, deployment methods, and challenges, aiming to provide insights for developers and businesses. The survey anticipates growth in modern PHP versio

In this article, we're going to explore the notification system in the Laravel web framework. The notification system in Laravel allows you to send notifications to users over different channels. Today, we'll discuss how you can send notifications ov
