Question

I’m trying to do a many-many database select, where I have events and music styles (among others). However since one event can have multiple music styles I decided to do a many-many relationship model.

This is what I created:

SELECT 
     a.* FROM music_types AS a, events_music_types AS b 
WHERE 
     a.id = b.music_type_id 
AND 
     b.event_id = events.ID

And inserted it into my code which now looks like this:

$query =    
"SELECT
    events.EVENT_NAME, events.start_datetime, events.end_datetime, events.VENUE_LOCATION, events.PARTY_TYPE, events.IMAGE_URL, events.ENTRANCE_PRICE, 
    venues.VENUE_NAME, venues.BEER_PRICE, venues.WINE_PRICE, SPIRITS_PRICE, 
    party_types.PARTYTYPE, 
    a.*
FROM events
INNER JOIN venues 
    ON events.VENUE_LOCATION = venues.ID
INNER JOIN party_types
    ON events.PARTY_TYPE = party_types.ID
INNER JOIN music_styles AS a, events_music_styles AS b
WHERE start_datetime >= '$DATE_START_SELECTED'
AND end_datetime < '$DATE_END_SELECTED' 
AND a.id = b.music_style_id 
AND b.event_id = events.ID
";
$result = mysql_query($query) or die(mysql_error());

echo "<table border='1'>
<tr>
<th> Poster </th>
<th> Event Name </th>
<th> Venue Name </th>
<th> Party Type </th>
<th> Entrance Price </th>
<th> Music </th>
<th> € of Beer </th>
<th> € of Wine </th>
<th> € of Spirits </th>
</tr>"; 

while($row = mysql_fetch_array($result, MYSQL_ASSOC)){

echo "<tr>";
echo "<td><IMG src='" . $row['IMAGE_URL'] . "'></td>";
echo "<td>" . $row['EVENT_NAME'] . "</td>";
echo "<td>" . $row['VENUE_NAME'] . "</td>";
echo "<td>" . $row['PARTYTYPE'] . "</td>";
echo "<td>" . $row['ENTRANCE_PRICE'] . "</td>";
echo "<td>" . $row['MUSIC_STYLE_NAME'] . "</td>";
echo "<td>" . $row['BEER_PRICE'] . "</td>";
echo "<td>" . $row['WINE_PRICE'] . "</td>";
echo "<td>" . $row['SPIRITS_PRICE'] . "</td>";
echo "</tr>"; 
}

However, while the code does get all of the music styles for an event, it doesn’t put it into one row but duplicates the row the amount of times that there are musical styles for each event.

How would I go about combining it into one row and separating the music styles with a comma? Thanks :)!

Answer 1

Change your query to –

$query =    
"SELECT
    events.EVENT_NAME,
    events.start_datetime,
    events.end_datetime,
    events.VENUE_LOCATION,
    events.PARTY_TYPE,
    events.IMAGE_URL,
    events.ENTRANCE_PRICE, 
    venues.VENUE_NAME,
    venues.BEER_PRICE,
    venues.WINE_PRICE,
    SPIRITS_PRICE, 
    party_types.PARTYTYPE,
    GROUP_CONCAT(music_styles.MUSIC_STYLE_NAME) AS MUSIC_STYLE_NAME
FROM events
INNER JOIN venues 
    ON events.VENUE_LOCATION = venues.ID
INNER JOIN party_types
    ON events.PARTY_TYPE = party_types.ID
INNER JOIN events_music_styles
    ON events.ID = events_music_styles.event_id
INNER JOIN music_styles
    ON events_music_styles.music_style_id = music_styles.id
WHERE start_datetime >= '$DATE_START_SELECTED'
AND end_datetime < '$DATE_END_SELECTED' 
GROUP BY events.ID
";

You also had a mix of join styles before which I have now corrected.