php - Prepared Statement with inner join, on multiple databases at the same time -

i sure has been answered, if know where.

databases
have 2 databases "conn" , "conn2"

conn host table called account. account has 2 columns: user_key,username 

conn2 has table called miles  miles has 3 columns: miles_key,miles_user_key, miles_amount 

what create leader board.

i pull miles_amount conn2 , use sum function total value. while using inner join on miles_user_key = user_key username conn.

i can fine , dandy single database, have no clue on how dual databases.

$lb_user_query = "  select miles_user_key, username, sum(miles_amount) 'miles'                      miles                      inner join account                          on account_stats.account_stats_account_key = miles.miles_user                      group miles.miles_user                      order miles desc"; $lb_user_stmt = $conn->prepare($lb_user_query); $lb_user_stmt->execute();                            $lb_user_stmt->bind_result($miles_user_key, $username, $miles); 

on side note, if wondering why account, , miles in 2 separate databases because have 2 separate sites same accounts populating each..

to pull data seperate databases, prepend table name database name. instead of using account, use conn.account, , instead of miles, use conn2.miles.