Oracle / SQL查找日期或最接近指定日期的日期

Question

I am trying to run a query within oracle which creates a value. The underlying table does not always contain a match for a specific date. So i have to either find the record with the date specified or find the closest date below the specified date.

SUM(CASE 
            WHEN S.VAL_SECURITY NOT IN ('GBP')
                AND E.SECURITY_ID NOT IN ('GBP')
                THEN (
                        (((amount) * - 1) / nvl(s.minor_per_unit, 1)) * (
                            SELECT EXCHANGE_RATE
                            FROM ISET.PREVIOUS_PRICES
                            WHERE ISET.PREVIOUS_PRICES.SECURITY_ID = E.SECURITY_ID
                                AND VAL_DATE = TO_DATE('05/08/2019', 'DD/MM/YYYY')
                            )
                        ) * (
                        SELECT EXCHANGE_RATE
                        FROM ISET.PREVIOUS_PRICES
                        WHERE SECURITY_ID = S.VAL_SECURITY
                            AND VAL_DATE = TO_DATE('05/08/2019', 'DD/MM/YYYY')
                        )
            WHEN S.VAL_SECURITY IN ('GBP')
                AND E.SECURITY_ID NOT IN ('GBP')
                THEN (
                        (((amount) * - 1) / nvl(s.minor_per_unit, 1)) * (
                            SELECT EXCHANGE_RATE
                            FROM ISET.PREVIOUS_PRICES
                            WHERE ISET.PREVIOUS_PRICES.SECURITY_ID = E.SECURITY_ID
                                AND VAL_DATE = TO_DATE('05/08/2019', 'DD/MM/YYYY')
                            )
                        )
            ELSE ((amount) * - 1) / nvl(s.minor_per_unit, 1)
END) GBP_VALUE

The code in question is

E.SECURITY_ID AND VAL_DATE = TO_DATE('05/08/2019', 'DD/MM/YYYY')

So assuming it doesn't find a record for the specified date then it needs to find the max date record closest to but below the specified date.

Any help would be greatly appreciated.

Thank you

Answer 1

I think you are looking for top 1 in this select :

SELECT EXCHANGE_RATE 
FROM ISET.PREVIOUS_PRICES 
WHERE ROWNUM = 1 
AND ISET.PREVIOUS_PRICES.SECURITY_ID=E.SECURITY_ID 
AND VAL_DATE <= TO_DATE('05/08/2019', 'DD/MM/YYYY') 
ORDER BY VAL_DATE DESC

Try this edited , with ROWNUM = 1 in the where condition

Answer 2

Could you try this? I haven't verified it.

    val_date =
(SELECT val_date
   FROM (SELECT MAX (b.val_date) val_date,
                MIN (TO_DATE ('05/08/2019', 'DD/MM/YYYY') - b.val_date)
                   diff
           FROM PREVIOUS_PRICES b
          WHERE     SECURITY_ID = E.SECURITY_ID
                AND status_date <= TO_DATE ('05/08/2019', 'DD/MM/YYYY')
         UNION ALL
         SELECT MIN (val_date),
                MIN (b.val_date - TO_DATE ('05/08/2019', 'DD/MM/YYYY'))
           FROM PREVIOUS_PRICES b
          WHERE     SECURITY_ID = E.SECURITY_ID
                AND status_date > TO_DATE ('05/08/2019', 'DD/MM/YYYY')
         ORDER BY 2)
  WHERE ROWNUM = 1)

Answer 3

Use one more embedded SQL Level

SELECT EXCHANGE_RATE
  FROM ISET.PREVIOUS_PRICES
 WHERE ISET.PREVIOUS_PRICES.SECURITY_ID = E.SECURITY_ID
       AND VAL_DATE = (
       SELECT MAX(val_date)
         FROM iset.previous_prices
        WHERE val_date <= TO_DATE ( '05/08/2019', 'DD/MM/YYYY' ) 
         and PREVIOUS_PRICES.SECURITY_ID = E.SECURITY_ID);