[edit]
2 Example #
use tempdb
go
--drop table test
create table test(gender nchar(1));
with temp(num)
as
(
select 1 num
union all
select num + 1 from temp
where num + 1 <= 10
)
insert test(gender)
select N'' -- 1000蟇
from temp a, temp b, temp c
union all
select N'' -- 10蟇
from temp;
create nonclustered index filtered_nix
on test(gender)
where gender = N'';
--full scan 襴
select * from test where gender = N'' --れ襦 Full Scan.
--index seek 襴
select * from test where gender = N'' --れ襦 Index Seek.
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