mySQLi filtering database results - php

Question

Okay i'm going to attempt to reword the question that was put on hold. I have a table in my database called anime this is what it looks like:
the code below mainly focuses on the tags row in the database which will has tags listed like this: tag1, tag2, tag3 etc..
I am trying to make a search that works via selecting keywords (tags) from a dropdown options menu (well 3 dropdown menus) since all the keywords (tags) are fixed and the tags within the database are fixed (the same) i can use
$tag_x = "tag1";
$tag_y = "";
$tag_z = "";
$tag_search = "%(?=.*$tag_x)(?=.*$tag_y)(?=.*$tag_z)%";
// Connect to Database
require 'connect.php';
$sql = "SELECT id, title, category FROM anime";
$result = $conn->query($sql);
if ($result->num_rows > 0)
{
// output data of each row
while ($row = $result->fetch_assoc())
{
$tags = $row["category"];
if (preg_match($tag_search, $tags)) {
echo $row["id"];
}
}
}
else
{
echo "0 results";
}
$conn->close();
this code can show matches for 1 - 3 keywords (tags)
the problem is i don't think this is a great way to do it and also i need to run it three times to get a list of results that have 3 matches first then 2 matches then 1 tag match, in a list.
////// OLD QUESTION BELOW THAT WAS PUT ON HOLD. (not sure if i should delete.) ///////////
Hello I am new to mysqli and databases in general I have been trying to find a way to filter down SELECT queries and display the results.
I have a database with lists of items that all have related tags and I am trying to show the row(s) and their information when a user makes a search query (via drop down menus). The data looks like this:
ID NAME TAGS CAT IMG_FILE_NAME
1 demo one tag1, tag2, tag3 ... something.png
2 demo two tag2, tag4 ... something.png
3 demo three tag0 ... something.png
4 demo four tag3, tag4, tag5 ... something.png
5 demo five ... ... something.png
6 ... ... ... ...
the search will work like this
<label for="x">I am looking for:</label>
<select id="x">
<option value="t1">Tag 1</option>
<option value="t2">Tag 2</option>
<option value="t3">Tag 3</option>
</select>
<label for="y">That has:</label>
<select id="y">
<option value="t4">Tag 4</option>
<option value="t5">Tag 5</option>
<option value="t6">Tag 6</option>
</select>
<label for="z">and is:</label>
<select id="z">
<option value="t7">Tag 7</option>
<option value="t8">Tag 8</option>
<option value="t9">Tag 9</option>
</select>
and the user may select x = tag 2 y = tag 5 z = tag 8
and then hit search or go and it would pull/show the results from the database with the tags the selected and failing that show the ones with the next closest matching tags (2 tags then 1 tag etc..)
can the WHERE statement do this?
I think 90% of my problem with finding an answer to this question is how i'm wording the question in the first place but after 3+ hours looking for something that works and not finding anything this seems like the best place to ask once again! any help would be amazing! and code/links to code would be greatly apperated!

Answer 1

The comma-separated values in your TAGS column are sub-optimal. You can, possibly, make this work like so
SELECT NAME, CAT, IMG_FILE_NAME
FROM item
WHERE TAGS LIKE CONCAT('%', ?tag1, '%')
AND TAGS LIKE CONCAT('%', ?tag2, '%')
AND TAGS LIKE CONCAT('%', ?tag3, '%')
where ?tag1 etc are the values provided by your user. But this sort of wildcard matching (WHERE TAGS LIKE '%tag3%', for example) is both error-prone and horribly slow if your table is large. (If your user gives you less than three tags, you need to use less than three WHERE clauses.
Do you want this to work well? Put the tags in their own tag table, with columns like so:
item_id
tag
So, if you item with id = 2 has tag2 and tag4, you'll have two rows in the tag table
2 tag2
2 tag4
Then, you can search with queries like this
SELECT COUNT(*) MATCHES, i.NAME, i.CAT, i.IMG_FILE_NAME
FROM tag t
JOIN item i ON t.item_id = i.id
WHERE t.tag = ?tag1
OR t.tag = ?tag2
OR t.tag = ?tag3
GROUP BY i.NAME, i.CAT, i.IMG_FILE_NAME
ORDER BY COUNT(*) DESC, i.NAME
This will give you a list of the items that match any or all the tags your user specified, with the ones that match more tags listed first.

Answer 2

yes, you should write something like:
SELECT field_a, field_b FROM table WHERE field_x='2' AND field_y='5' AND field_z='8'
it is obvious that you have to adapt it to your table and to your field names but can give you a hint.
Based on your comment you should do something like:
SELECT field_a, field_b FROM table WHERE tags='2, 5, 8'
but note that this will look for the exact string. So if you have a row where tag = '5,2,8' (same tags but different order) you will not get the result.
It is better (IMHO) to use three columns like tag_1, tag_2 and tag_3 and store each value in a single column? So that my first example will become
SELECT field_a, field_b FROM table WHERE tag_1='2' AND tag_2='5' AND tag_3='8'