How to sum hours which is varchar2 data type in oracle

Question

Hi My table is like this
emp_ngtshthrs (empno number(10),nightshifthrs varchar2(20));
now I want sum employee nightshifthrs how to do sum of hrs, this is my hours data 01:00,05:00,08:00,10:00,07:00 and 09:00
I want sum the varchar2 type of hours how to do it? and I want to display even the sum is more than 24:00 hrs

Answer 1

Well, first you have posted your question in the wrong forum. You should have posted your question in the PL/SQL forum.
The second problem I see is that you are being too generic when you have your employees enter their night shift hours worked. If you are able, I recommend you modify your table to record hours seperately from minutes and make the columns of type NUMBER instead of type VARCHAR2(). Then you can use simply arithmatic to total the hours and minutes worked.
If you are locked into your table and can't change it, then you can convert the characters to numbers and then perform your summary arithmatic on the values. For example:
  1  with tab1 as (
  2  select 10 as empno, '01:00' as nightshifthrs from dual union all
  3  select 10 as empno, '05:00' as nightshifthrs from dual union all
  4  select 10 as empno, '08:00' as nightshifthrs from dual union all
  5  select 10 as empno, '10:00' as nightshifthrs from dual union all
  6  select 10 as empno, '07:00' as nightshifthrs from dual union all
  7  select 10 as empno, '09:00' as nightshifthrs from dual)
  8  select sum(to_number(replace(nightshifthrs,':','.'))) AS hours_worked
  9* from tab1
SQL> /
HOURS_WORKED
          40
SQL> Of course, if your users can and do enter minutes, then that complicates the example I provided. You will have to convert the minutes to decimal, sum the amount, then convert the decimal back to time and add this to your hours. For example:
  1  with tab1 as (
  2  select 10 as empno, '01:15' as nightshifthrs from dual union all
  3  select 10 as empno, '05:00' as nightshifthrs from dual union all
  4  select 10 as empno, '08:30' as nightshifthrs from dual union all
  5  select 10 as empno, '10:00' as nightshifthrs from dual union all
  6  select 10 as empno, '07:45' as nightshifthrs from dual union all
  7  select 10 as empno, '09:00' as nightshifthrs from dual)
  8  select sum(to_number(substr(nightshifthrs,1,2))) + SUM(to_number(SUBSTR(nightshifthrs,4,5)))/60
  9* from tab1
SQL> /
HOURS_WORKED
        41.5
SQL> Hope this helps.
Craig...