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What is max doing across fields in a de-duplication ?

P: n/a
Greetings folks,

Just curious if anyone knows what the following would produce:
SELECT
MAX( ECP_SUPPORT_DED_EMAIL.CD_TYP_CMPGN) CD_TYP_CMPGN,
MAX(ECP_SUPPORT_DED_EMAIL.CELL_ID) CELL_ID,
ECP_SUPPORT_DED_EMAIL.CLIC_CUST_ID CUSTID,
MAX( ECP_SUPPORT_DED_EMAIL.ADDRESS) CONTACTED_PARTYID,
MAX( ECP_SUPPORT_DED_EMAIL.CONTACTED_PARTY_ID_TYPE )
FROM
ECP_SUPPORT_DED_EMAIL
group by CUSTID

For a given CUSTID, and assuming all fields are character and there
are duplicates, will it randomly select the MAX value of any of these
fields across duplicates, or will it randomly select a custID and
retain that row's attributes with integrity?

thanks!
Jack
Jul 19 '05 #1
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2 Replies


P: n/a
Jan
I have no idea, but let`s guess - it will return the max values of the
rows for each custid?

ja***********@yahoo.com (Jack) wrote in message news:<20**************************@posting.google. com>...
Greetings folks,

Just curious if anyone knows what the following would produce:
SELECT
MAX( ECP_SUPPORT_DED_EMAIL.CD_TYP_CMPGN) CD_TYP_CMPGN,
MAX(ECP_SUPPORT_DED_EMAIL.CELL_ID) CELL_ID,
ECP_SUPPORT_DED_EMAIL.CLIC_CUST_ID CUSTID,
MAX( ECP_SUPPORT_DED_EMAIL.ADDRESS) CONTACTED_PARTYID,
MAX( ECP_SUPPORT_DED_EMAIL.CONTACTED_PARTY_ID_TYPE )
FROM
ECP_SUPPORT_DED_EMAIL
group by CUSTID

For a given CUSTID, and assuming all fields are character and there
are duplicates, will it randomly select the MAX value of any of these
fields across duplicates, or will it randomly select a custID and
retain that row's attributes with integrity?

thanks!
Jack

Jul 19 '05 #2

P: n/a
ja***@pobox.sk (Jan) wrote in message news:<81**************************@posting.google. com>...
I have no idea, but let`s guess - it will return the max values of the
rows for each custid?

ja***********@yahoo.com (Jack) wrote in message news:<20**************************@posting.google. com>...
Greetings folks,

Just curious if anyone knows what the following would produce:
SELECT
MAX( ECP_SUPPORT_DED_EMAIL.CD_TYP_CMPGN) CD_TYP_CMPGN,
MAX(ECP_SUPPORT_DED_EMAIL.CELL_ID) CELL_ID,
ECP_SUPPORT_DED_EMAIL.CLIC_CUST_ID CUSTID,
MAX( ECP_SUPPORT_DED_EMAIL.ADDRESS) CONTACTED_PARTYID,
MAX( ECP_SUPPORT_DED_EMAIL.CONTACTED_PARTY_ID_TYPE )
FROM
ECP_SUPPORT_DED_EMAIL
group by CUSTID

For a given CUSTID, and assuming all fields are character and there
are duplicates, will it randomly select the MAX value of any of these
fields across duplicates, or will it randomly select a custID and
retain that row's attributes with integrity?

thanks!
Jack


First there is nothing RANDOM about it.

MAX() returns the largest value of the COLUMN.

so for mytable:
cmpgn cell custid
xxxx abc 234
aaaa xyz 234

select max(cmpgn), max(cell), custid
from mytable group by custid ;

returns
max(cmpgn) max(cell) custid
xxxx xyz 234

hth,
ed
Jul 19 '05 #3

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