Query for a Date Range

Question

Hi folks,
hope everyone had a good weekend. Have a problem at hand and hoping to find a solution. Here is what I need to do. I need to find out the following based on Dates.
Currently, we have Students who pay certain kinds of fees and that is detrmined based on their Fee Codes. I will listing the table structure in a bit.
Query 1:
1. I need to find out Students who did not have a Fee Code back in September 1st, 2009 and had a Fee Code on September 1st, 2010.
Query 2:
2. Find out students who had a Fee Code back in September 01st, 2009 and do not have a Fee Code in September 01,2010.
Now, by saying that a Student no longer has a Fee Code in September 01,2009/2010, it's not just the fact that record does not exist but also that there is an Expiry Date. So, basically, when a new record is created in the table, the previous record's GRAD_EXP_EFF_DATE gets stamped with SYSDATE.
Table GRAD_FEE_STRUCTURE_HIST
GRAD_STU_ID        NOT NULL  VARCHRA2(6)
GRAD_STU_FEE_CODE  NOT NULL  VARCHAR2(6)
GRAD_EFF_FEE_DATE  DATE
GRAD_EXP_FEE_DATE  DATE
GRAD_CREATE_DATE   DATE
GRAD_CREATE_USERID VARCHAR2(10)Any help is appreciated. I am using Oracle 9i.

Answer 1

Hi,
Try something like this:
SELECT       grad_stu_id
FROM       grad_fee_structure_hist
GROUP BY  grad_stu_id
HAVING       COUNT ( CASE
                  WHEN  DATE '2010-09-01'  BETWEEN  grad_eff_fee_date
                                           AND        grad_exp_fee_date
                THEN  1
            END
          )     > 0
AND       COUNT ( CASE
                  WHEN  DATE '2009-09-01'  BETWEEN  grad_eff_fee_date
                                           AND        grad_exp_fee_date
                THEN  1
            END
          )     = 0
;If a NULL grad_fee_exp_date means that the row is currently in force, then use something like
NVL ( grad_fee_exp_date
    , DATE '9999-12-31'
    )instead of the raw date.
I hope this answers your question.
If not, post a little sample data (CREATE TABLE and INSERT statements) and the results you want from that data. Explain how you get those results from that data, giving specific examples.
Always say what version of Oracle you're using.
Edited by: Frank Kulash on Sep 13, 2010 11:08 AM
Changed date comparisons to BETWEEN.