Control stmt CASE vs IF - Which is better

Question

Hi,
I'm in the process of retrieving data from a table that has millions of rows. Now I need to count the numbers of rows where a particular field,TR_STATUS is either 'A','G' or 'K'. I have three different variables to hold the count on the rows with the respective values in the field, TR_STATUS I'm retrieving the rows into nested tables and am using a FOR loop, inside which a IF or a case should be written inorder to perform the count based on the value. From performance perspective, which one of these two control statements is preferred. please advise
Thanks

Answer 1

Or even
CREATE TABLE testtable AS
SELECT DECODE(TRUNC(DBMS_RANDOM.VALUE(1,4)), 1, 'A', 2,'B', 3,'C') AS tr_status
FROM   user_tables;
Table created.
SELECT SUM(DECODE(tr_status,'A',1)) AS count_a
     , SUM(DECODE(tr_status,'B',1)) AS count_b
     , SUM(DECODE(tr_status,'C',1)) AS count_c
FROM   testtable;
   COUNT_A    COUNT_B    COUNT_C
        12          6         11
1 row selected.orSELECT COUNT(DECODE(tr_status,'A','#')) AS count_a
     , COUNT(DECODE(tr_status,'B','#')) AS count_b
     , COUNT(DECODE(tr_status,'C','#')) AS count_c
FROM   testtable;
   COUNT_A    COUNT_B    COUNT_C
        12          6         11
1 row selected.Whatever you use though, SQL will be fast and slogging around a loop with IF statements will be slow.