Queries from Diffrent Tables How to Join Suggest PLease (PHP)(SQL) - php

Question

I need help regarding JOIN tables to get category name & author name from other tables.
for articles site I have Three Tables
articles
categories
users
Articles Table structure :
id
title
slug
content
category
author
date
I save category ID & user ID in articles table with each article
While Displaying Articles for a category I use this:
(just some draft idea not full code)
localhost/testsite/category.php?cat=category-slug
$catslug = ($_GET["cat"]);
//GET CAT ID from category table from slug
$qry = "SELECT * from category WHERE slug='$catslug';
$res = mysql_query($qry) or die("Error in Query");
$ans = mysql_fetch_array($res);
$cid = $ans['id'];
$catname = $ans['title'];
<h2><?php echo $catname; ?></h2>
//after getting cat-id query to get article of that ID
$aqry = select * from article where category=$cid ORDER BY date";
$ares = mysql_query($aqry) or die("Error in Query");
$aans = mysql_fetch_array($ares))
$aid = $aans['author'];
//then another query to get author name from users
select username from users where id=$aid
I m learning PHP & not much familiar with JOIN statement & combining queries
need help/suggestions hw can I achieve same with JOIN tables instead of different queries to get catname and author name from tables.
Thanks

Answer 1

This should do what you want
SELECT distinct c.title, U.Username
from category C join article A on A.category=C.id
join users U on U.id=A.author
WHERE C.slug= :catslug

Answer 2

Assuming Category id is foreign jey in article table
Try this query
select username from users
where id in (
select author from category cat
inner join article art
on cat.category_id =art.category_id
where cat.slug= $cat
order by art.date desc )

Answer 3

$q = "SELECT article.*
FROM article
LEFT JOIN category
ON article.category = category.ID
LEFT JOIN users
ON article.author = users.ID
WHERE article.slug = :slug";
:slug is where you would insert (bind if you're using PDO) $_GET['slug']

Answer 4

You can do some different thing with a SQL request. You can do some join in your SQL request but you can also do another SELECT statement in your request Like
SELECT SOMETHINGS FROM A_TABLE WHERE (SELECT ANOTHER_THING FROM ANOTHER_TABLE WHERE VALUE =1
But this statement will only work if you have 1 result in your second request
If you want to join two table with some value, you'll have to do it like this
SELECT something FROM a_table AS alias1 JOIN another_table AS alias2
ON alias1.value1 = alias2.value1 and .....
You can compare all the value that you want from one table to another and you can also join more than two table and the ON key word is not requested by sql syntax you can just do
SELECT * FROM table_1 join table_2
and it will show you all thje data from two table but be sure that this is the data you want this kind of little query can have some big result and slow down your app
you can read more there http://dev.mysql.com/doc/refman/5.0/en/join.html

Answer 5

First off, you should write a stored proc... but here's how you would get articles by categoryID that includes both the category name and user name.
Given the following table structures:
article
---------
articleID <- primary key
title
slug
content
categoryID <- foreign key
userID <- foreign key
createdDT
category
--------
categoryID <- primary key
categoryName
user
--------
userID <- primary key
userName
Here's how to write the query using joins:
SELECT a.title, a.slug, a.content, a.createdDT, c.categoryName, u.userName
FROM dbo.article a
JOIN dbo.category c on a.categoryID = c.categoryID
JOIN dbo.user u on a.userID = u.userID
WHERE a.categoryID = #categoryID
Here's an article from Microsoft on JOINs - http://msdn.microsoft.com/en-us/library/ms191517.aspx