Question

I have quite a bit of knowledge about SQL queries.

I’m trying to make gallery, and I need to select categories from table “cat_photos”, which contain rows (id,name,cover,photo) and count number of photos from table “photos” which contain rows (id,thumb,photo,category).

Here is code which i use:

1) Selecting categories

$query = mysql_query("SELECT * FROM cat_photos ORDER BY ID DESC");
               while($data = mysql_fetch_array($query)) {       
        echo "<li><a href='photos.php?cat=$data[id]'><img src='galleries/categories/$row[image]' alt='$row[name]' /></a>
              <div class='photodesc'><div class='catname'><a href='photos.php?cat=$row[id]'>$row[name]</a></div>
              <div class='catcount'>Number of photos in category</div></div></li>"; }

2) Counting number of photos in category

$query = mysql_query("SELECT category, COUNT(photo) FROM photos GROUP BY category") or die(mysql_error());
               while($row = mysql_fetch_array($query)){
        echo "Number of photos is ". $row['COUNT(photo)'] ." in cateogry ". $row['category'] .".";
        echo "<br />"; }

Separated all works, but I can’t find a way to merge them into one query.
I have googleing for “UNION”, “JOIN”, “LEFT JOIN” options in MySql query but I could’t together the pieces.

I wonder if this is in general possible?
How in order that query look like?

Answer 1

Try this, it should work :

SELECT cat_photos.*, count(photos.id) as number_photos
FROM cat_photos
LEFT JOIN photos ON photos.category = cat_photos.id
GROUP BY cat_photos.id, cat_photos.name, cat_photos.image
ORDER BY cat_photos.id

The number of photos will be accessible trough $row['number_photos'].