So that begs the question - is there an index on the date column?
The original problem was that the delete, based on a "where" involving
a to_date of a data column, seemed to go on forever(and not end).
Ronald J Kimball [[EMAIL PROTECTED]] wrote:
> On Thu, Oct 18, 2001 at 11:41:54AM -0400, Yibin Dong wrote:
> > It depends on which database you are using. In Oracle,
> > when TO_DATE() is employed within where clause, all indexes
> > will be useless. Oracle will do a range scan instead of
> > index row scan.
>
> I don't think that's accurate. The index is useless if a function is used
> on the value of the column. In Javier's query:
>
> > > >$sql = "DELETE FROM ft_t_ispc WHERE LAST_CHG_TMS <
> > > >TO_DATE('$final_date','MM/DD/YYYY')";
>
> the TO_DATE function is not being used on the column; it's being used on
> the value the column is being compared to.
>
> I tried a query like this:
>
> SELECT count(*)
> FROM mytable
> WHERE mydate < TO_DATE('2000-01-01', 'YYYY-MM-DD')
>
> and Oracle did a fast full scan of the index on mydate.
>
>
> If I had done a TO_CHAR on the mydate column instead, then the index would
> have been useless.
>
>
> Ronald
