Rewrite NVL/TRUNC to make index usage .

Question

Hi,
I'm on 9.2.0.8 and got query like that
select * from table
where      
        TRUNC (SYSDATE) BETWEEN TRUNC (NVL (data_od, SYSDATE))
                       AND TRUNC (NVL (data_do, SYSDATE));Is there any better way I can rewrite this to make index on data_od data_do ubeing used ?
Regards
GregG

Answer 1

smart000 wrote:
select * from table
where      
        TRUNC (SYSDATE) BETWEEN TRUNC (NVL (data_od, SYSDATE))
AND TRUNC (NVL (data_do, SYSDATE));The requirement reflected by the sql seems odd (although it may be what u want) You want to check that that today's date should be between 2 date fields. But, If any of the 2 fields is null then you are replacing by today's date
1. data_od cannot be a future date
2. data_do cannot be a past date
3. if data_od = null and data_do = null then you are thru', not check required
4. if data_od = null then data_do has to be equal to trunc(sysdate) to satisfy the condition
Please check whether the above in relation to your requirement, it may prompt something to rewrite the query.It's basically saying show me everything where data_od and data_do are set to today or either are null.
4. if data_od = null then data_do has to be equal to trunc(sysdate) to satisfy the conditionThat's not correct. If data_od is null then trunc(sysdate) has to be <= trunc(sysdate) i.e. ignore the condition. Same is true (with >=) for data_do