How to use url string id# to select row from db?

[shauno7]

Hi, I'm new to the backend php mysql development, so if you could explain slowly and clearly, it would be much appreciated.

In my database, I have each row labelled with an 'ID' number. The question is, how can I pull a string from a url for example:
www.mydomain.com/index.php?id=3
where I can then echo all the content in the row with ID 3?

I know this may seem very basic for some of you, but if you could show me an example it would be great, as I have been looking for tutorials on the internet, and there have been none so far.
Thanks...

[vinyl-junkie]

Here's the code you would need to pull that id into your script:

$id = $_GET['ID'];

Then I assume you'll have some kind of query against your database similar to this:

SELECT * from tablename where table-id = '$id';

Hope this helps.

[arborint]

For the URL :www.mydomain.com/index.php?id=3

I would add one thing to vinyl-junkie 's code:

// use intval() to avoid SQL injection
$id = intval($_REQUEST['id']);

$sql = "SELECT * from tablename where id = '$id';"; 

[shauno7]

ok, once i selected that row, how do i extract the entries within the row?
Supposing I have the columns: 'id' , 'title', 'description'.

[Lats]

Try this...

// use intval() to avoid SQL injection 
$id = intval($_REQUEST['id']); 

$sql = "SELECT * from tablename where id = '$id';"; 

$result = mysql_fetch_array(mysql_query($sql)) or die(mysql_error());

echo $result['id'],$result['title'],$result['description']; 

[shauno7]

Wow, thanks everyone, it works perfectly. Exactly what I needed.
Just one more question, what does it mean 'to avoid sql injection'? Is it some security issue?

[Lats]

...what does it mean 'to avoid sql injection'? Is it some security issue?

Yep, check this thread...
http://www.sitepoint.com/forums/show...threadid=60643

[shauno7]

btw, i want to display all the id links on a links page and I want to sort it descendingly. ie. where id5 is on the top of the list and id1 at the bottom.
Could you show me an example of how to do this.
This is much appreciated.

[Lats]

Something like this...

$sql = "SELECT * from tablename order by id desc"; 
$sql_result = mysql_query($sql)) or die(mysql_error());

while($result = mysql_fetch_array($sql_result); 
{
    echo "<br>";
    echo $result['id'],$result['title'],$result['description']; 
} 

[pompopom]

btw, i want to display all the id links on a links page and I want to sort it descendingly. ie. where id5 is on the top of the list and id1 at the bottom.
Could you show me an example of how to do this.
This is much appreciated.

just a tip:
all php functions alfabetically ordened (check mysql_ section)
http://www.php.net/quickref.php

mysql manual
http://dev.mysql.com/doc/mysql/en/index.html

sure they helped me a lot

greetz,
koen

[shauno7]

Alright! Thanks you guys. Been of great help. Do you know what other functions would be good if implementing this kind of database driven webpages?

[pompopom]

Alright! Thanks you guys. Been of great help. Do you know what other functions would be good if implementing this kind of database driven webpages?

like I said, check the mysql_section from the php quick reference manual
(search for all the functions in the list starting with mysql_ (they're ordened alfabetically) )

when you can't figure out how to achieve your goal: just post a new thread. It's of no use that everybody here starts to give a list of most common or most used functions, as every "goal" has it's own approach and differs from wich function to use best...

when you don't understand the use of a function you can post it here too

greetz,
koen

[vinyl-junkie]

Well, you could peruse the php manual for all the different functions that are available (see manual links in prior posts here). However, I'd like to encourage you to consider buying Kevin's Yank's PHP book. In my opinion, it's one of the best learning tools you'll find for building database driven web page content, and in fact is what I used to do just that on my own website.

Hope this helps.

[pompopom]

Well, you could peruse the php manual for all the different functions that are available (see manual links in prior posts here). However, I'd like to encourage you to consider buying Kevin's Yank's PHP book. In my opinion, it's one of the best learning tools you'll find for building database driven web page content, and in fact is what I used to do just that on my own website.

Hope this helps.

I forgot to mention that
vinyl-junkie is right, Kevin's book is a good learning tool indeed

[shauno7]

Yes, i might get the book, however i'm not that keen on spending too much money. Do any of you know a good website which offers these kind of tutorials?

[vinyl-junkie]

W3Schools

[spikeZ]

some websites do give very good tutorials however, a reference book like Kevin's might seem like alot to spend now but compare that to how much time you will spend trawling the internet for tutorials.

Spend a little bit now and have a reference and guide in your hands, it will save you more in the long term.
Just my 2penneth!

SpikeZ

[shauno7]

Ok, thanks. I have managed to select a row from the one id string. Now, the question is, how do I select from multiple variables, supposing I have a column for 'type', 'id', 'title' and 'description'. How would I query a row with a type with 'single' and an 'id' with '3'?

[pompopom]

change your MySQL query accordingly

check http://www.mysql.com

greetz,
koen

[Lats]

...how do I select from multiple variables, supposing I have a column for 'type', 'id', 'title' and 'description'. How would I query a row with a type with 'single' and an 'id' with '3'?

Post what you have so far, we can take it from there.

[shauno7]

basically i have this:
// use intval() to avoid SQL injection
<?php
$id = intval($_REQUEST['id']);

$sql = "SELECT * from tablename where id = '$id';";

$result = mysql_fetch_array(mysql_query($sql)) or die(mysql_error());

echo $result['id'],$result['title'],$result['description'];
?>

but now, i want to add another column called 'type' so I can sort the rows by the 'type' and 'id' using the url string.

[vinyl-junkie]

Just change this one statement like so:

$sql = "SELECT * from tablename where id = '$id' ORDER BY type, id;";

[Lats]

It doesn't look like much sorting is going to be required, as your sql is pulling out data by ID, usually just 1 record.

[shauno7]

What happens if I want to pull out a perticular type and a specific id of that type. ie. 'type'=multi and 'id' = 5?
This is because I have two different contents, single and multi, and I want to pull out specific ids for each one.

[shauno7]

Could someone show me how to accomplish this?