MySQL queries, selecting field from one of many databases -

i have remarks table can linked number of other items in system, in case of example we'll use bookings, enquiries , referrals.

thus in remarks table have columns

remark_id | datetime    | text | booking_id | enquiry_id | referral_id 1         | 2014-06-28  | abc  | 0          | 8          | 0 2         | 2014-06-27  | def  | 3          | 0          | 0 2         | 2014-05-31  | ghi  | 0          | 0          | 10 

etc...

each of item tables have field called name. when want select remark likelihood i'll need name.

i'd achieve single query, getting 2d array follows:

['remark_id'=>1, 'datetime'=>'2014-06-28', 'text'=>'abc', 'name'=>'harold'] 

however query i'd expect use be

 select r.remark_id,r.datetime,r.text  ,b.name book,rr.name referral,e.name enquiry  remarks r  left join bookings b on b.book_id=r.book_id  left join referrals rr on rr.referral_id=r.referral_id  left join enquiries e on e.enquiry_id=r.enquiry_id 

leaving me output

['remark_id'=>1, 'datetime'=>'2014-06-28', 'text'=>'abc', 'book'=>'harold', 'referral'=>'', 'enquiry'=>''] 

and more processing before or during rendering view.

is there way write query such fill field first not null string encountered in 1 of joined tables?

please suggest using different database system if know mysql doesn't provide way i'm asking. if it's case can't done there's no business sense in rewriting system anyway, i'd ask!

one way achieve nested if statements:

if(b.name not null, b.name, if(rr.name not null, rr.name, e.name)) name 

one drawback gives implicit priority books? not sure if issue.

perhaps main drawback, though, kind of "magical" , has goofy syntax might more clear handle cases in controller after all.