sql server - Remove Duplicates ... With NULLs -


in ms sql server trying remove duplicates table nulls. que groans. lots , lots of nulls. bottom line need retain 1 copy of duplicate record or without nulls. wantnull act normal record value of "null" duration of operation, , go being real null. possible? there simpler solution?

table1 looks like:

uid        data1    data2    1                  null         2                  null        3           b        abc      4           b        abc        5           c        null       6           d        ghj

i want command throw away line 2 , 4 , keep rest. (the select testing.)

;select uid, data1, data2  table1 t  not exists (     select 1     table1 t2            t2.data1 = t.data1       , t2.data2 = t.data2       , t2.uid >= t.uid       )     , data1 not null

note: select distinct not work duplicates have different timestamps.

this should do:

;with cte (     select  *,             rn = row_number() over(partition data1,data2 order uid)     table1 ) delete --select * cte rn > 1

updated following comment

ok, if having issues delete amount of rows, could try creating table id's want delete , batch delete (you have test batch row amount, though). idea (assuming uid pk):

;with cte (     select  *,             rn = row_number() over(partition data1,data2 order uid)     table1 ) select [uid] rowstodelete cte rn > 1;  create index i_uid on rowstodelete([uid]);  while 1=1 begin     delete top (10000)     table1 t     inner join rowstodelete l           on t.[uid] = l.[uid]     if @@rowcount < 10000 break; end

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