Calculating difference of a single date field

Question

Greetings
I have a table as below
Test_case_id Execution_Date Execution_id
100 7/1/2009 1
100 7/5/2009 2
100 7/20/2009 3
I want to write a query that gives me the no of days between two executions.
I want the result to be like
4 days (between the first two executions)
15 days (between the next two executions)
Please help

Answer 1

You can try:
with t as(
select 100 as Test_case_id, to_date('7/1/2009', 'mm-dd-yyyy') Execution_Date, 1 Execution_id from dual union all
select 100 as Test_case_id, to_date('7/5/2009', 'mm-dd-yyyy') Execution_Date, 2 Execution_id from dual union all
select 100 as Test_case_id, to_date('7/20/2009', 'mm-dd-yyyy') Execution_Date, 3 Execution_id from dual)
select to_char((select min(execution_date)
             from t  t2
          where t2.execution_date > t1.Execution_date) - t1.Execution_Date)||' days' Diff
from t t1
where t1.execution_date < (select max(execution_date)
              from t  t2 )
DIFF
4 days
15 daysMiguel