分组还是加入搜索查询？

Question

I'm trying to have my websites search box be able to search multiple tables in one query.

So if a user searches for the users display_name which is stored in ptb_profiles they get any users with the matching name or if they search by nationality which is stored in ptb_stats they get all the users with that nationality displayed.

When i did this originally by using SELECT * FROM ptb_users, ptb_stats, ptb_profiles I got duplicate search results and the same results were being displayed multiple times, so I tried to do avoid this and have each result only displayed once by Grouping and using union all but that didnt work.

now ive tried this:

$query_for_result=mysql_query("SELECT display_name, location, gender, contact_number FROM ptb_profiles WHERE display_name LIKE '%".$query."%' OR location LIKE '%".$query."%' OR gender LIKE '%".$query."%' OR contact_number LIKE '%".$query."%' JOIN SELECT email, subscription FROM ptb_users WHERE email like '%".$query."%' OR subscription like '%".$query."%' JOIN SELECT nationality, hobbies, local_station FROM ptb_stats WHERE nationality like '%".$query."%' OR hobbies like '%".$query."%' OR local_station like '%".$query."%' 
        LIMIT 5");

but this just brings up the following error:

Warning: mysql_fetch_array() expects parameter 1 to be resource, boolean given in /Applications/XAMPP/xamppfiles/htdocs/PTB1/includes/mod_sidebar/search.php on line 31

Can someone please tell me where I'm going wrong?

Answer 1

This wouldn't be the only way to do it. But you can do your search on multiple joined tables and fetch a distinct list of users easily if you apply a GROUP BY to your query. Assuming all your tables relate via an ID column something like this might work...

SELECT u.* FROM ptb_users u
INNER JOIN ptb_stats s ON s.user_id=u.id
INNER JOIN ptb_profiles p ON p.user_id=u.id
WHERE "this or that"
GROUP BY u.id

Change your joins to LEFT JOINS if its possible a user doesn't have a record in ptb_stats or ptb_profiles...

Answer 2

mysql_fetch_array() complains about $query_for_result not being a query result. You must check the return value from mysql_query() . It returns false, if there's some problem with your SQL statement. So do at least

$sql = "select ...";
$result = mysql_query($sql) or die("Error in $sql: " . mysql_error());

to prevent and diagnose such errors.