mysql select UNION with AND problem -


in database, table friendship has id, username , friendusername. when user accept other user friend, 1 row of record saved in table (not 2 rows). want random select 15 users , display pictures, mysql code :

<?php $query120 = "select frenusername friendship username='{$username2}' union select username friendship friendusername='{$username2}' , rand()<(select ((15/count(*))*10) friendship) order rand() limit 15"; $result120 = mysql_query($query120,$connection) or die (mysql_error()); confirm_query($result120);  while($userinfo120 = mysql_fetch_array($result120)){     $frenusername= $userinfo120['frenusername'];     $username = $userinfo120['username']; //this hold empty value, why?      $query121 = "select picturemedium users username='{$frenusername} or username='{$username}' limit 1";     //display picture     } } ?>

my problem 1 : why $username hold empty value?

my problem 2 : statement and rand()<(select ((15/count(*))*10) friendship) order rand() limit 15" random select 15 records table. supposedly need write on both union statements right? (meaning need write 2 times). if so, show 30 records instead of 15 records. should change become 8/count limit 8 each? or there other way avoid duplicate , statement?

if need random set of 15 friends of username2, don't need union:

(select username  friendship  (friendusername='{$username2}' or  username='{$username2}') ,  rand()<(select ((15/count(*))*10) friendship)  order rand()  limit 15)

the union select either select. in sql, first select of usernames in friendship table, second select random 15, union select either of 2 selects record if in either of 2 select results. that's why you're seeing users.


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