Help with quierying a table with varchar as dates

Question

guys need a little help im close but i just can't close the deal.
i have a table that the field is dataytped as varchar2 but it holds a date like such '20100615' todays date.
I know the first thing you guys are going to say is that this should be formatted as a date but it is not my table and i have to deal with this.
any how here is the problem im trying to query for a range of dates and im having one hell of a time doing it.
as you cant tell from my query below im atempting to bring back only 15days worth of data by date.
can someone please point out the obvious. I've been at it for a day now trying to get this to work.
select DISTINCT to_date(fwvitals_date, 'YYYYMMDD') "fwvitals_date"
FROM fwvitals
where fwvitals_date
between (((SELECT MAX(fwvitals_date)FROM FWVITALS)))
AND ((select to_CHAR(sysdate-15, 'YYYYMMDD') from dual))

Answer 1

Hi,
user633029 wrote:
guys need a little help im close but i just can't close the deal.
i have a table that the field is dataytped as varchar2 but it holds a date like such '20100615' todays date.
I know the first thing you guys are going to say is that this should be formatted as a date but it is not my table and i have to deal with this.You're absolutely correct!
any how here is the problem im trying to query for a range of dates and im having one hell of a time doing it.
as you cant tell from my query below im atempting to bring back only 15days worth of data by date.
can someone please point out the obvious. I've been at it for a day now trying to get this to work.
select DISTINCT to_date(fwvitals_date, 'YYYYMMDD') "fwvitals_date"
FROM fwvitals
where fwvitals_date
between (((SELECT MAX(fwvitals_date)FROM FWVITALS)))
AND ((select to_CHAR(sysdate-15, 'YYYYMMDD') from dual))"WHERE x BETWEEN y AND z" is equivalent to
"WHERE x >= y AND x <= z".
If y > z, then no rows will ever qualify, and if y is the gratest value in your table, then (probably) very few rows, perhaps only 1 will satisfy the condition even if z > y.
What exactly are you trying to do?
It helps if you post a little sample data (CREATE TABLE and INSERT statements) and the results you want from that data. If the results are conditional, give a couple of examples, e.g,, "If I run the query at any time on June 15, I want ... but if it's June 16, then I want ..."
If you want the most recent 15 days, including today (that is, when run on June 15, you want June 1 through June 15) then:
SELECT DISTINCT 
     fwvitals_date
FROM      fwvitals
WHERE       fwvitals_date     BETWEEN     TO_CHAR (SYSDATE - 14, 'YYYYMMDD')
               AND     TO_CHAR (SYSDATE,      'YYYYMMDD')
;Fortunately, the strings are in a format such that sorting is meaningful, so you don't have to run TO_DATE on each one, and get conversion errors.
Edited by: Frank Kulash on Jun 15, 2010 9:52 PM