How To Avoid Divide by Zero?

From: Sean <sharasin_at_mbakercorp.com>
Date: Tue, 07 Dec 1999 15:48:45 GMT
Message-ID: <x%934.58$LLj.393378@dca1-nnrp1.news.digex.net>

I would appriciate any help with this query. The sixth line where I am doing the division has the potential to cause a divide by zero error. Is there any way that I can return a null value if I hit the div by 0?

Thanks in advance.

SELECT
 READING_DATE AS READ_DATE,

 MIN(reading_time) AS READ_TIME,
 SUM(DECODE(INSTRUMENT_NAME, '01-1', HEADWATER)) AS "01-1_HEADWATER",
 SUM(DECODE(INSTRUMENT_NAME, '01-1', TAILWATER)) AS "01-1_TAILWATER",
 SUM(DECODE(INSTRUMENT_NAME, '01-1', ((WATER_SURFACE - TAILWATER) /

((HEADWATER - TAILWATER) / 100)))) AS "01-1_DELTA_HEAD",  SUM(DECODE(INSTRUMENT_NAME, '01-1', WATER_SURFACE)) AS "01-1_WATERSURFACE",  LOC_CODE
FROM
 P_READINGS R1
WHERE
(READING_DATE <= TO_DATE('12/31/1973', 'MM/DD/YYYY')) AND
(READING_DATE >= TO_DATE('01/01/1973', 'MM/DD/YYYY')) AND
(UPPER(LOC_CODE) = 'CAP') AND
(INSTRUMENT_NAME IN ('01-1')) AND

 READING_TIME = (SELECT MIN(R2.READING_TIME) FROM
 P_READINGS R2
WHERE
 R2.LOC_CODE = R1.LOC_CODE AND
 R2.INSTRUMENT_NAME = R1.INSTRUMENT_NAME AND  TRUNC(R2.READING_DATE, 'DD') = TRUNC(R1.READING_DATE, 'DD')) GROUP BY
 READING_DATE,
 LOC_CODE
ORDER BY
 READING_DATE Received on Tue Dec 07 1999 - 09:48:45 CST