Conditional reults in a query

Hi all

My db structure is (table r)

id,a,b,c
1,1,1,USA
2,1,2,national
3,1,3,USA

I a m looking for a query which satisfy a=1 and c=usa.If ‘USA’ is not avilable I need to get second row (national).How can I do this in mysql ? and If USA is avilable I need only first and third row.

Is it poosible to get in a single query,please help

I tried this but not getting exact results

select * from r where a = 1 and
(

CASE 
WHEN (c = 'USA') 
THEN 
c= 'USA

ELSE c = 'national'



   

END

)

rows in a database table don’t have positions, so “second” is not possible

is there some other way to determine which row(s) you want if USA is not available?

solution stored procedure