Can any body tell me what is the problem what is the problem in my
case statement?

CREATE PROCEDURE AAABBB(
PORTALID INTEGER)
RETURNS (
AID INTEGER,
NAME VARCHAR(50))
AS
BEGIN
FOR SELECT
MP.RoleID,
case
when MP.RoleID = -1 then 'All Users'
when MP.RoleID = -2 then 'Superuser'
when MP.RoleID = -3 then 'Unauthenticated Users'
else R.RoleName
end
AS 'RoleName'

FROM AAA MP
LEFT JOIN BBB R ON MP.RoleID = R.RoleID
INTO :AID, :Name
DO SUSPEND;

END