Getting multiple rows of the same thing from database - php

Question

I'm having some issues with this mysql database i got from school. I'm getting duplicate rows with the same name but different quantities. I would suppose that this is because 'inventory' contains columns with the same name as in 'sets'. But i really can't get it to work. Thank you in advance for all your help.
Database schematic (in Swedish, but the titles are in English.):
http://weber.itn.liu.se/~stegu76/TNMK30-2016/legodatabasen.pdf
I'm very new to this so any tips would be appreciated.
$setidquery = "SELECT inventory.Quantity, inventory.ItemID, inventory.ColorID, colors.Colorname, parts.Partname, sets.SetID, sets.Year, inventory.ItemtypeID FROM `inventory`, `parts`, `colors`, `sets` WHERE sets.SetID='$_COOKIE[setid]' AND inventory.ItemID=parts.PartID AND inventory.ColorID=colors.ColorID ORDER BY Partname ASC LIMIT 1000";
echo "<table class=\"table\">";
echo "<tr><th>Quantity:</th><th>Year:</th><th>Partname:</th><th>ItemID:</th><th>SetID</th><th>Image:</th></tr>";
while($row = mysqli_fetch_array($result)){
$prefix = "http://www.itn.liu.se/~stegu76/img.bricklink.com/";
$Year = $row['Year'];
$Quantity = $row['Quantity'];
$ItemID = $row['ItemID'];
$ColorID = $row['ColorID'];
$Partname = $row['Partname'];
$SetID = $row['SetID'];
$ItemtypeID = $row['ItemtypeID'];
$imagesearch = mysqli_query($conn, "SELECT * FROM `images` WHERE ItemTypeID = '$ItemtypeID' AND ItemID = '$ItemID' AND ColorID = '$ColorID' ");
$imageinfo = mysqli_fetch_array($imagesearch);
if($imageinfo['has_jpg']) {
$filename = "$ItemtypeID/$ColorID/$ItemID.jpg";
} else if($imageinfo['has_gif']) {
$filename = "$ItemtypeID/$ColorID/$ItemID.gif";
} else {
$filename = "noimage_small.png";
}
echo "<tr>
<td>$Year</td>
<td>$Quantity</td>
<td>$Partname</td>
<td>$ItemID</td>
<td>$SetID</td>
<td><img src=\"$prefix$filename\" alt=\"Part $ItemID\"/></td>
</tr>";
}
echo "</table>";
Here is the query formatted for readability:
SELECT inventory.Quantity,
inventory.ItemID,
inventory.ColorID,
colors.Colorname,
parts.Partname,
sets.SetID, sets.Year,
inventory.ItemtypeID
FROM `inventory`, `parts`, `colors`, `sets`
WHERE sets.SetID='$_COOKIE[setid]'
AND inventory.ItemID=parts.PartID
AND inventory.ColorID=colors.ColorID
ORDER BY Partname ASC LIMIT 1000;

Answer 1

The problem is that inventory, parts and colors are not joined to sets.
It is OK to do the joins in the where clause, but, as Strawberry says we prefer to write the joins in the from clause now. I think that makes them easier to read, which helps to spot missing joins.
Here is your select statement (formatted to help me see what is going on):
select
inventory.quantity,
inventory.itemid,
inventory.colorid,
colors.colorname,
parts.partname,
sets.setid,
sets.year,
inventory.itemtypeid
from
inventory,
parts,
colors,
sets
where
sets.setid='$_cookie[setid]' and
inventory.itemid = parts.partid and
inventory.colorid = colors.colorid
order by
partname asc
limit 1000;
And here is the join version. I've shown the missing join with "?" where you need to add something:
select
inventory.quantity,
inventory.itemid,
inventory.colorid,
colors.colorname,
parts.partname,
sets.setid,
sets.year,
inventory.itemtypeid
from
inventory
join
parts
on inventory.itemid = parts.partid
join
colors,
on inventory.colorid = colors.colorid
join
sets
on set.? = ?.?
where
sets.setid='$_cookie[setid]'
order by
partname asc
limit 1000;
The important thing is that there is no join to sets. I would guess that there are three sets (for each of the examples shown anyway). Because you have not said how to join to sets the query returns the other rows once for each set, in other words it joins to every set because you haven't restricted the join in any way.
If you want to learn more about SQL there are many options. My website is www.thedatastudio.net.