MAX(), GROUP BY errors - db2

Question

On DB2 V9 Z/Os
The query below three rows.
SELECT J01_REGION, I20_MMS_NO, I20_CONSUMER_ID, I21_CONSUMER_ID, I21_CASE_ID,
I42_FIN_MGR_PROV, J01_PROVIDER, I21_CASE_OPEN_DT, I42_FM_BEG_DT
FROM SERDB.I20_CONSUMER_T INNER JOIN SERDB.I21_CONS_CASE_T ON I20_CONSUMER_ID =
I21_CONSUMER_ID
INNER JOIN SERDB.I42_FIN_MGR_T ON I21_CASE_ID = I42_CASE_ID
INNER JOIN SERDB.J01_PROVIDER_T ON I42_FIN_MGR_PROV = J01_PROVIDER
WHERE J01_REGION = 2
AND I20_CONSUMER_ID = 96603
What I would like is for the query to return just one row by using the MAX values for I21_CASE_OPEN_DT & I42_FM_BEG_DT. If I use:
SELECT J01_REGION, I20_MMS_NO, I20_CONSUMER_ID, I21_CONSUMER_ID, I21_CASE_ID, MAX
(I21_CASE_OPEN_DT), MAX(I42_FM_BEG_DT), I42_FIN_MGR_PROV, J01_PROVIDER
FROM SERDB.I20_CONSUMER_T INNER JOIN SERDB.I21_CONS_CASE_T ON I20_CONSUMER_ID =
I21_CONSUMER_ID
INNER JOIN SERDB.I42_FIN_MGR_T ON I21_CASE_ID = I42_CASE_ID
INNER JOIN SERDB.J01_PROVIDER_T ON I42_FIN_MGR_PROV = J01_PROVIDER
WHERE J01_REGION = 2
AND I20_CONSUMER_ID = 96603;
I receive: SQL0122N A SELECT statement with no GROUP BY clause contains a column name or expression and a column function in the SELECT clause, or a column name or expression is contained in the SELECT clause but not in the GROUP BY clause. SQLSTATE=42803
If I use:
SELECT J01_REGION, I20_MMS_NO, I20_CONSUMER_ID, I21_CONSUMER_ID, I21_CASE_ID,
I42_FIN_MGR_PROV, J01_PROVIDER, I21_CASE_OPEN_DT, I42_FM_BEG_DT
FROM SERDB.I20_CONSUMER_T INNER JOIN SERDB.I21_CONS_CASE_T ON I20_CONSUMER_ID =
I21_CONSUMER_ID
INNER JOIN SERDB.I42_FIN_MGR_T ON I21_CASE_ID = I42_CASE_ID
INNER JOIN SERDB.J01_PROVIDER_T ON I42_FIN_MGR_PROV = J01_PROVIDER
WHERE J01_REGION = 2
AND I20_CONSUMER_ID = 96603
AND MAX(I21_CASE_OPEN_DT)
AND MAX(I42_FM_BEG_DT);
I recieve: SQL0199N The use of the reserved word "AND" following "AND" is not valid. Expected tokens may include: "MICROSECONDS MICROSECOND SECONDS SECOND MINUTES MINUTE HOURS". SQLSTATE=42601
Does anyone have a suggestion as to what else I could do?
Thank you

Answer 1

The second error tells you all you need to know:
A SELECT statement with no GROUP BY clause contains a column name or expression and a column function in the SELECT clause, or a column name or expression is contained in the SELECT clause but not in the GROUP BY clause
If you use aggregates (MAX, MIN, etc.) you must group by all other fields in the select statement, which you have not done.
Taking your second query, and adding the GROUP BY clause gets us this:
SELECT J01_REGION, I20_MMS_NO, I20_CONSUMER_ID, I21_CONSUMER_ID, I21_CASE_ID,
MAX (I21_CASE_OPEN_DT), MAX(I42_FM_BEG_DT), I42_FIN_MGR_PROV, J01_PROVIDER
FROM SERDB.I20_CONSUMER_T INNER JOIN SERDB.I21_CONS_CASE_T ON I20_CONSUMER_ID =
I21_CONSUMER_ID
INNER JOIN SERDB.I42_FIN_MGR_T ON I21_CASE_ID = I42_CASE_ID
INNER JOIN SERDB.J01_PROVIDER_T ON I42_FIN_MGR_PROV = J01_PROVIDER
WHERE J01_REGION = 2
AND I20_CONSUMER_ID = 96603
GROUP BY J01_REGION, I20_MMS_NO, I20_CONSUMER_ID, I21_CONSUMER_ID, I21_CASE_ID,
I42_FIN_MGR_PROV, J01_PROVIDER;