Select max date from a table with multiple records

Question

I need help writing an SQL to select max date from a table with multiple records.
Here's the scenario. There are multiple SA_IDs repeated with various EFFDT (dates). I want to retrieve the most recent effective date so that the SA_ID is unique. Looks simple, but I can't figure this out. Please help.
SA_ID CHAR_TYPE_CD EFFDT CHAR_VAL
0000651005 BASE 15-AUG-07 YES
0000651005 BASE 13-NOV-09 NO
0010973671 BASE 20-MAR-08 YES
0010973671 BASE 18-JUN-10 NO

Answer 1

Hi,
Welcome to the forum!
Whenever you have a question, post a little sample data in a form that people can use to re-create the problem and test their ideas.
For example:
CREATE TABLE     table_x
(     sa_id          NUMBER (10)
,     char_type     VARCHAR2 (10)
,     effdt          DATE
,     char_val     VARCHAR2 (10)
INSERT INTO table_x (sa_id,  char_type, effdt,                          char_val)
     VALUES     (0000651005, 'BASE',    TO_DATE ('15-AUG-2007', 'DD-MON-YYYY'), 'YES');
INSERT INTO table_x (sa_id,  char_type, effdt,                          char_val)
     VALUES     (0000651005, 'BASE',    TO_DATE ('13-NOV-2009', 'DD-MON-YYYY'), 'NO');
INSERT INTO table_x (sa_id,  char_type, effdt,                          char_val)
     VALUES     (0010973671, 'BASE',    TO_DATE ('20-MAR-2008', 'DD-MON-YYYY'), 'YES');
INSERT INTO table_x (sa_id,  char_type, effdt,                          char_val)
     VALUES     (0010973671, 'BASE',    TO_DATE ('18-JUN-2010', 'DD-MON-YYYY'), 'NO');
COMMIT;Also, post the results that you want from that data. I'm not certain, but I think you want these results:
`    SA_ID LAST_EFFD
    651005 13-NOV-09
  10973671 18-JUN-10That is, the latest effdt for each distinct sa_id.
Here's how to get those results:
SELECT    sa_id
,         MAX (effdt)    AS last_effdt
FROM      table_x
GROUP BY  sa_id
;