sql - Is there any particular downside to adding MAX() to all fields to weed out duplicate rows? -


i using sql server 2016. have large table 30+ columns. when pull data need there duplicated rows. imagine because there difference in 1 of columns i'm not using, purposes data same. have done change

select     [reference], [name], [postcode], [type], [amount]     [my table]

to 

select     [reference], max([name]), max([postcode]), max([type]), max([amount])     [my table] group      [reference]

is cause problems? either in hugely increased processing time or potential errors?

your approach fine. more typical approach is:

select distinct [reference], [name], [postcode], [type], [amount] [my table] t;

i expect have same performance group by, can check. sometimes, may optimize differently.

an alternative method is:

select [reference], [name], [postcode], [type], [amount] (select t.*,              row_number() on (partition [reference], [name], [postcode], [type], [amount]                                 order (select null)                                ) seqnum       [my table] t      ) t seqnum = 1;

you might want test , see performs better.


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