Question

I’m stuck on the inner join scenario for my tables. Can you please help me? What I am doing wrong here?

Here is the scenario that I’m trying to do:

I have billing and shipping country/states columns which I am trying to populate with inner join, but somehow it is not working. Thanks a lot for your help:

 $sql = $this->connection->query("SELECT * FROM ".TBL_USERS." 
    INNER JOIN ".TBL_USER_LEVEL." ON ".TBL_USERS.".userlevel = ".TBL_USER_LEVEL.".user_level_id 
    INNER JOIN ".TBL_COUNTRIES." ON ".TBL_USERS.".country OR ".TBL_USERS.".bcountry = ".TBL_COUNTRIES.".country_id
    INNER JOIN ".TBL_STATES." ON ".TBL_USERS.".states OR ".TBL_USERS.".bstates  = ".TBL_STATES.".states_id
    WHERE ".TBL_USERS.".username = '$username'");

i changed the query to; and the error im gettin is

PHP Fatal error: Uncaught exception ‘PDOException’ with message ‘SQLSTATE[42000]: Syntax error or access violation: 1066 Not unique table/alias: ‘countries” in

 $sql = $this->connection->query("SELECT * FROM ".TBL_USERS." 
    INNER JOIN ".TBL_USER_LEVEL." ON ".TBL_USERS.".userlevel = ".TBL_USER_LEVEL.".user_level_id 
    INNER JOIN ".TBL_COUNTRIES." ON ".TBL_USERS.".country = ".TBL_COUNTRIES.".country_id
    INNER JOIN ".TBL_COUNTRIES." ON ".TBL_USERS.".bcountry = ".TBL_COUNTRIES.".country_id
    INNER JOIN ".TBL_STATES." ON ".TBL_USERS.".states = ".TBL_STATES.".states_id

    INNER JOIN ".TBL_STATES." ON ".TBL_USERS.".bstates = ".TBL_STATES.".states_id

    WHERE ".TBL_USERS.".username = '$username'");

OK here is correct syntax thanks a lot to @Tiberiu-Ionuț Stan

$sql = $this->connection->query("SELECT * FROM ".TBL_USERS." 
    LEFT JOIN ".TBL_COUNTRIES." ON ".TBL_USERS.".country = ".TBL_COUNTRIES.".country_id 

   LEFT JOIN ".TBL_COUNTRIES." AS ".TBL_COUNTRIES."_b ON ".TBL_USERS.".bcountry=".TBL_COUNTRIES."_b.country_id

    INNER JOIN ".TBL_USER_LEVEL." ON ".TBL_USERS.".userlevel = ".TBL_USER_LEVEL.".user_level_id 
    LEFT JOIN ".TBL_STATES." ON ".TBL_USERS.".states = ".TBL_STATES.".states_id 

    LEFT JOIN ".TBL_STATES." AS ".TBL_STATES."_b ON ".TBL_USERS.".bstates=".TBL_STATES."_b.states_id


    WHERE ".TBL_USERS.".username = '$username'");

Answer 1

You can use OR and AND inside join statements.
I do it all the time.
Here’s one that works:

  LEFT JOIN `currencies` ON (
   `currency_foreign`=`invoice_entry_amount_currency`
   AND
   `currency_reference`='".$strTransformToCurrency."'
   AND
   `currency_date`=FLOOR(`invoice_paid_timestamp`/86400)*86400
  )

Problem is here:

   INNER JOIN ".TBL_COUNTRIES." ON ".TBL_USERS.".country = ".TBL_COUNTRIES.".country_id
   INNER JOIN ".TBL_COUNTRIES." ON ".TBL_USERS.".bcountry = ".TBL_COUNTRIES.".country_id

MySQL can’t decide on which relation to join the countries table (because MySQL thinks .country and .countryb can be different – so after join it doesn’t know which columns will be returned or used for conditions and ordering).

Try it like this:

  INNER JOIN ".TBL_COUNTRIES." ON ".TBL_USERS.".country = ".TBL_COUNTRIES.".country_id
  INNER JOIN ".TBL_COUNTRIES." AS ".TBL_COUNTRIES."_b ON ".TBL_USERS.".bcountry=".TBL_COUNTRIES."_b.country_id

In case you have really big tables, do an EXPLAIN with the full final query including conditions and ordering to find out if MySQL is doing a table copy because of “TBL_USERS AS TBL_USERS_B”.