sql - Oracle case inside where clause -

this simple question, i've read details using case in where clause, couldn't able make clear idea how use it. below sample query:

1    select * dual 2    (1 =1) 3     , (sysdate+1 > sysdate) 4     , (30 > 40) 5     , (25 < 35); 

i have procedure i_value in parameter. need ignore 4th line if i_value 's' , need ignore 5th line if i_value 't'.

thanks in advance.

i think best way solve problem:

select * dual (1 = 1)       , (sysdate + 1 > sysdate)       , case             when i_value = 's'                               case                   when (25 < 35)                     1                     else 0                 end             when i_value = 't'                               case                   when (30 > 40)                     1                     else 0                 end           end = 1; 

of course, use dynamic sql, it'd more difficulty , less effectively.