I have a query and when I run it I get the error message ORA-00907: missing parenthesis. When I replace the CASE expression with either x = g and or y = g and it runs as expected.

SELECT *
FROM
table1,
table2,
table3,
table4,
table5,
table6,
table7,
table8
WHERE
a = b and
c = d and
e = d and
CASE strfldvar
    WHEN 'BROKEN_ARROW' THEN (x = g)
    WHEN 'BROKEN_BOX'   THEN (y = g)
ELSE -1
end 
and
f = h and
i = j

What am I doing wrong here?