How to avoid DIVIDE BY ZERO error in an SQL query

Have you tried using NULLIF()?

 SELECT ( 100 / NULLIF( 0, 0 ) ) AS value ;

Oracle Doc
http://www.oracle-base.com/articles/9i/ANSIISOSQLSupport.php#NULLIFFunction

Another example
http://www.bennadel.com/blog/984-Using-NULLIF-To-Prevent-Divide-By-Zero-Errors-In-SQL.htm

If you want to ignore such records you can use a subquery

SELECT  YEAR, period, round((1- rej_sum / recd_sum)*100, 0) FROM(  SELECT YEAR, sum(rej_qty) rej_sum, sum(recd_qty) recd_sum  FROM   TAB_A  WHERE  sid = '200'  AND    sdid IN ('4750')  AND  (       (          YEAR ='2011'       AND    period IN('01_JAN')       )  OR  (      YEAR = '2010'       AND    period IN ('02_FEB','03_MAR','04_APR','05_MAY','06_JUN','07_JUL','08_AUG','09_SEP','10_OCT','11_NOV','12_DEC')       )  )  group by year, period)WHERE recd_sum <> 0;

If you want to keep them and handle the division by zero issue, you can use decode or case

SELECT  YEAR, period, DECODE(recd_qty, 0, NULL, round((1- sum(rej_qty) / sum(recd_qty))*100, 0)) 

round(ISNULL(((1- sum(rej_qty)) / NULLIF( (sum(recd_qty))*100), 0 )),0),0)

If you replace your division using NULLIF to set a NULL when there is divide by zero, then an ISNULL to replace the NULL with a 0 - or indeed whatever value you want it to.