sql - Where Clause Case Statement; ORA-00907: missing parenthesis -

i have query , when run error message ora-00907: missing parenthesis. when replace case statement either x = g and or y = g and runs expected.

select * table1, table2, table3, table4, table5, table6, table7, table8 = b , c = d , e = d , case strfldvar     when 'broken_arrow' (x = g)     when 'broken_box'   (y = g) else -1 end  , f = h , = j 

what doing wrong here?

case expression, not predicate (i.e condition) : 'returns' typed value , can not contain predicate result (in then parts). in case (assuming else -1 means 'no match') :

and g = case strfldvar   when 'broken_arrow' x   when 'broken_box'   y    else null -- never match, if g null end 

although think simpler replace :

and (      (strfldvar = 'broken_arrow' , x = g)    or (strfldvar = 'broken_box' , y = g) )