sql - Update value for flag column -


i want create stored procedure updates value current flag y or n comparing values of c1 , c2 , set recent 1 y , older n. in result set below, row 1 , 2 have same values c2 , c2, want set current flag recent y , older n. row 3 in below result set not have duplicate want y.

10  12  9    1985-06-10     null 10  12  60   2015-09-10     null 3   5   23   2001-09-10     null 1   1   96   2010-09-10     null 1   1   71   2016-09-10     null 

you can in standard sql using correlated subquery:

update t     set flag = (case when date = (select max(date) t t2 t2.c1 = t.c1 , t2.c2 = t.c1)                      'y' else 'n'                 end); 

specific databases might have alternative methods, should work in database.


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