Is there a way to do a join with cases

Question

Is there a way to make a join with cases?

Something like

select * from abba 
   case when a=b then 
      join acdc on abba.id=acdc.id
   when b=c then 
      join bebop on abba.id=bebop.id 
   end

Is there a way to do this?

Best regards Joe

Answer 1

The usual way to do this is to LEFT JOIN both tables and select the value based on the CASE condition:

SELECT *, CASE WHEN a=b THEN acdc.myField ELSE bebop.myField END AS myField
  FROM abba 
       LEFT JOIN acdc ON abba.id=acdc.id 
       LEFT JOIN bebop ON abba.id=bebop.id