execute block
returns (TEST varchar(100))
as
declare ST varchar(200);
begin
 ST = 'execute block
       returns (TEST varchar(100))
       as
       begin
       -- строчный комментарий
        /* блочный комментарий */
        select d.RDB$RELATION_ID from RDB$DATABASE d  into :TEST;
        suspend;
       end' ;

 execute statement :ST into :TEST;
 suspend;
end

execute block
returns (TEST varchar(100))
as
declare ST varchar(200);
begin
 ST = 'execute block
       returns (TEST varchar(100))
       as
       begin
        select d.RDB$RELATION_ID from RDB$DATABASE d  into :TEST;
        suspend;
       end' ;

 execute statement :ST into :TEST;
 suspend;
end