ORA-06502：PL / SQL：数字或值错误：Oracle SQL查询中的字符串缓冲区太小

Question

I want to calculate the time difference between two dates in Oracle sql query. I have written the following query:

DECLARE
 v_time varchar2(40); 
 diff_hours varchar2(40); 
 BEGIN
 select substr(((select date_time from observation_measurement where observation_measurement_id=2861971)), 1,17)
 into v_time
 from dual;

 dbms_output.put_line(v_time);

 select 24 * (to_date('06-25-2014 09:46:36', 'MM-DD-YYYY hh24:mi:ss') 
             - to_date(v_time, 'YY-MM-DD hh24:mi:ss')) into diff_hours 
       from dual;
END;

The first select statement returns correct result. When I am trying to calculate the time difference from current date to the previous calculated date then it is showing error. How can I get the correct result?

Thanks!!!!

Answer 1

Increasing the size of diff_hours variable working. Thanks Krishna. :-)

Answer 2

Make diff_hours a NUMBER variable instead of a VARCHAR2 variable!

Of course you can make diff_hours long enough to hold all the insignificant decimals your query produces, but declaring it VARCHAR2 is pointless anyway!

Answer 3

Hi I have made some corrections in your query . Tell me if that works

DECLARE
 v_time varchar2(40);
-- Increase the size  
 diff_hours varchar2(200); 
 BEGIN
 select substr(((select date_time from observation_measurement where observation_measurement_id=2861971)), 1,17)
 into v_time
 from dual;

 dbms_output.put_line(v_time);
-- using the same format mask for both the dates
 select 24 * (to_date('06-25-2014 09:46:36', 'MM-DD-YYYY hh24:mi:ss') 
             - to_date(v_time, 'MM-DD-YYYY hh24:mi:ss')) into diff_hours 
       from dual;
END;

Answer 4

You can increase diff_hours and it might work in some cases, but the problem is it might not work in other cases.

To be sure, you need explisitly convert number to string (example with 2 digits after dot):

select trunc(24*...., 2) into diff_hours