mysql query to insert photo details in database tables - php

Question

I want to build a query to insert photo details in database tables. Here's my tables structure:
photos(photo_id, photo_title, caption, ....)
tags(tag_id, tag_name)
tag_asc(tag_id, photo_id)
A photo has title, caption, and tags array. I want to:
Insert photo_title and caption in photos table.
Insert each of tag from tags array in tags table.
Insert tag_id and photo_id in tag_asc table (to link tags with photos).
I have come up with following three queries to do above task.
mysql_query("INSERT INTO photos (photo_title, caption)
VALUES ($title, $caption)");
$photo_id = mysql_insert_id(); //get photo_id
foreach ($tags as $tag){
mysql_query("INSERT INTO tags (tag_name)
VALUES ($tag)");
$tag_id = mysql_insert_id(); //get tag_id
mysql_query("INSERT INTO tag_asc (tag_id, photo_id)
VALUES ($tag_id, $photo_id)");
}
My question
If the above approach is good, or if there is more efficient way to do same thing?

Answer 1

Most of what you're doing looks fine. The main problem I see is the potential for duplicate tags.
It would be better to check if a tag exists and fetch the existing tag's ID if it does, rather than creating a new tag each time. This would prevent duplicate tag names from being inserted into the tags table. If you know each tag is unique, this could speed things up later — for example, you could search photos by their tag IDs rather than having to do some messy JOIN stuff.
Give tags.tag_name a unique index if it doesn't have one already.
Use the following function to fetch a tag ID. If the tag already exists, the existing row ID will be returned. If not, a new row will be created and its ID will be returned.
-
function select_or_create_tag($tag_name) {
$tag_name = addslashes($tag_name);
$result = mysql_query("SELECT id FROM tags WHERE tag_name='$tag_name'");
if ( mysql_num_rows($result) > 0 )
return mysql_result($result, 0, 0);
$insert = mysql_query("INSERT INTO tags (tag_name) VALUES ('$tag_name')");
return mysql_insert_id($insert);
}
Example usage, based on your code:
mysql_query("INSERT INTO photos (photo_title, caption)
VALUES ($title, $caption)");
$photo_id = mysql_insert_id();
foreach ( $tags as $tag ) {
$tag_id = select_or_create_tag($tag);
mysql_query("INSERT INTO tag_asc (tag_id, photo_id)
VALUES ($tag_id, $photo_id)");
}
Also:
Make sure you have non-unique indices set up on tag_asc.tag_id and tag_asc.photo_id for faster querying.
As OMG Ponies mentioned, it might be worth converting this code to a stored SQL procedure. That would get rid of a lot of the overhead involved with making all these SQL queries individually.