Find date sequence in SQL Server -


i'm trying find maximum sequence of days customer in data. want understand max sequence of days specific customer made. if enter app in 25/8/16 , 26/08/16 , 27/08/16 , 01/09/16 , 02/09/16 - max sequence 3 days (25,26,27).

in end (the output) want 2 fields: custid | maxdaysequence

i have following fields in data table: custid | orderdate(timestemp)

for exmple: custid orderdate 1 25/08/2007 1 03/10/2007 1 13/10/2007 1 15/01/2008 1 16/03/2008 1 09/04/2008 2 18/09/2006 2 08/08/2007 2 28/11/2007 2 04/03/2008 3 27/11/2006 3 15/04/2007 3 13/05/2007 3 19/06/2007 3 22/09/2007 3 25/09/2007 3 28/01/2008

i'm using sql server 2014.

thanks

there trick, if have incrementing number ordered date subtracting number of days dates same if consecutive. this:

select custid,         min(orderdate) start_of_group,        max(orderdate) end_of_group,        count(*) num_days (    select custid, orderdate           row_number() on (partition  custid order orderdate) rn ) x group custid, dateadd(day, - rn, orderdate);

you take result of , pull out max number of days solve problem:

select custid, max(num_days) longest (   select custid,           count(*) num_days   (      select custid, orderdate             row_number() on (partition  custid order orderdate) rn   ) x   group custid, dateadd(day, - rn, orderdate) ) y group custid

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