Count of is null of datetime field

Hi All,

Im having a problem with count of null values fields and indexes...

I have a table (tb_Propose) with around 8 million lines.

A field Dt_flag -- Datetime

An index Ix_Dt_flag, nonclustered, with field Dt_flag, only

When I do the "select count(*) from tb_Propose where Dt_Flag is null", the results comes so different from real... When I do "reindex", on first time, the select works fine. However, from the second execution the results coming wrong. The database is with option "Auto Update Stats" enabled.

Results:

select count(*) from tb_Propose where Dt_flag is null
select count(*) from tb_Propose where Dt_flag is not null
select count(*) from tb_Propose

----
8405710

(1 row(s) affected)

----
3818428

(1 row(s) affected)

----
8978255

(1 row(s) affected)

[]s
Carlos Eduardo
Bizplace
www.bizplace.com.brThat is really strange. Perhaps you could build a simple test case that exhibits this behavior and post the code so I can try it out on my system?