Question

lets say we have an array like this

from a mysql function like

function getGroups($limit = 10) {
    $data = $this->fetchAll ( 'SELECT gid, `group`, information, tag FROM groups 
    GROUP BY tag LIMIT ' . $limit );
    return $data;
}

Resulting

array
  0 => 
    array
      'gid' => string '6' (length=1)
      'group' => string 'Media' (length=5)
      'tag' => string 'advertising' (length=11)
  1 => 
    array
      'gid' => string '8' (length=1)
      'group' => string 'Fashion' (length=10)
      'tag' => string 'shorts' (length=7)
  2 => 
    array
      'gid' => string '7' (length=1)
      'group' => string 'Automotive' (length=8)
      'tag' => string 'cars' (length=5)
  3 => 
    array
      'gid' => string '1' (length=1)
      'group' => string 'Fashion' (length=7)
      'tag' => string 'tshirt' (length=6)

i need to display somehow to this ( something like )

array
   0 =>
     array
       'group' => string 'Media'
       'tags' 
          array 
          0 => string 'advertising'

   1 =>
     array
       'group' => string 'Fashion'
       'tags'
          array 
          0 => string 'short'
          1 => string 'tshirt'   
   2 =>
     array
       'group' => string 'Automotive'
       'tags'
          array
          0 => 'cars'  

simpler

group      tag
media      advertising
fashion    short
fashion    tshirt
automotive cars

to

media
  advertising
fashion
  short
  tshirt
automotive
  cars

what is the best way to do this? from php array? or from the mysql ?

Answer 1

Are you trying to get a list of groups, plus all the tags for each group? GROUP_CONCAT() is the right way to get the tag list but you want to be grouping by group, not by tag:

function getGroups($limit = 10) {
    $data = (array) $this->fetchAll (
        'SELECT `group`,
        GROUP_CONCAT(DISTINCT `tag` ORDER BY `tag`) AS `tags`
        FROM `groups`
        GROUP BY `group` LIMIT ' . $limit
    );
    foreach ($data as $i => $row) {
        $data[$i]['tags'] = explode(',', $row['tags']);
    }
    return $data;
}