How to set a session id to a value after using a case-when statement?

[Charles Ndethi]

Hi I want to set the session id to a value after evaluating the request_time using a case when statement.

here 's the table

userinput_id         session_id          request_time               keyword
     1                                   2011-03-04 08:23:45        free    
     2                                   2011-03-04 08:25:50        free

when the keyword is entered request_time ( TIMESTAMP) is stored automatically , I also want to set the session id automatically after evaluating the request_time in a case when statement:

create procedure upd_userinput(in request_time TIMESTAMP,out time TIME, out user_session_id INT)     
begin      
set time = time(request_time);    
case  
when time < '09:15:00' && time > '08:15:00' then      
set user_session_id = 1; 

when time < '10:15:00' && time > '09:15:00' then
set user_session_id = 2;  

when time < '11:15:00' && time > '10:15:00' then
set user_session_id = 3;

when time < '12:15:00' && time > '11:15:00' then
set user_session_id = 4;

when time < '13:15:00' && time > '12:15:00' then
set user_session_id = 5;

when time < '14:15:00' && time > '13:15:00' then
set user_session_id = 6;

when time < '15:15:00' && time > '14:15:00' then
set user_session_id = 7;

when time < '16:15:00' && time > '15:15:00' then
set user_session_id = 8;

when time < '17:15:00' && time > '16:15:00' then
set user_session_id = 9;

when time < '18:15:00' && time > '17:15:00' then
set user_session_id = 10;

when time < '19:15:00' && time > '18:15:00' then
set user_session_id = 11;

when time < '20:15:00' && time > '19:15:00' then
set user_session_id = 12;

else set user_session_id = 0;

end case;  
end //

The procedure executes.(it returns OK, 0 rows affected) on mysql terminal. but when i call it (it calls fine again) and check the table nothing has changed, is it because i use set rather than insert or what could be the problem? Is there an easier way?

Thanks. Please help.

[Rabbit]

An update SQL is of the form:

UPDATE TableName SET FieldName1 = Value, FieldName2=Value