Max is used to fetch the record having maximm value say for some particular column like select max ( field 1 ) ....
and for group by see F1 help on select ,i pasted the same below -
Variants:
1. ... GROUP BY f1 ... fn
2. ... GROUP BY (source_text)
Variant 1
... GROUP BY f1 ... fn
Effect
Groups database table data in a SELECT command on one line in the result set. A group is a set of lines which all have the same values in each column determined by the field descriptors f1 ... fn.
... GROUP BY f1 ... fn always requires a list in the SELECT clause. If you use field descriptors without an aggregate funciton in the SELECTclause, you must list them in the GROUP BY f1 ... fn clause.
Example
Output the number of passengers, the total weight and the average weight of luggage for all Lufthansa flights on 28.02.2001:
DATA: count TYPE I, sum TYPE P DECIMALS 2, avg TYPE F.
DATA: connid TYPE sbook-connid.
SELECT connid COUNT( * ) SUM( luggweight ) AVG( luggweight )
INTO (connid, count, sum, avg)
FROM sbook
WHERE
carrid = 'LH' AND
fldate = '20010228'
GROUP BY connid.
WRITE: / connid, count, sum, avg.
ENDSELECT.
Notes
... GROUP BY f1 ... fn is not supported for pooled and cluster tables.
The columns f1, ..., fn must not be of the type STRING or RAWSTRING.
Variant 2
... GROUP BY (source_text)
Effect
Works like GROUP BY f1 ... fn if the variable source_text contains the list f1 ... fn as ABAP source code.
Note
The same restrictions apply to this variant as to GROUP BY f1 ... fn.
Example
Output all Lufthansa departure points with the number of destinations:
DATA: BEGIN OF wa.
INCLUDE STRUCTURE spfli.
DATA: count TYPE I.
DATA: END OF wa.
DATA: field_list TYPE STRING,
group_by_list TYPE STRING,
count TYPE I.
field_list = 'CITYFROM COUNT( * ) AS COUNT'.
group_by_list = 'CITYFROM'.
SELECT DISTINCT (field_list)
INTO CORRESPONDING FIELDS OF wa
FROM spfli
WHERE
carrid = 'LH'
GROUP BY (group_by_list).
WRITE: / wa-cityfrom, wa-count.
ENDSELECT.
Note
Performance:
If aggregates and groups are formed by the database system and not just by the application server, this helps to reduce considerably the volume of data that has to be transported from the database server to the application server.
Bluesky
