Question

I’m having some difficulty in understanding the following WHERE clause in a T-SQL (SQL Server 2000/2005) query:

update #tempTable
SET
    Total_Avg=isnull(TerminationReason,'terminated'),
    Individual_Subscriptions=null,
    Business_Subscriptions=null,
    Other_subscriptions=null,
    -- snip. 10 more fields set to NULL.
    PMIE_BI=null,
    Digital_Editions_BI=null
where
(
    AbcTerminationDate<=dbo.fnGetPeriodFinalDate(@periodid)
    and (AbcTerminationDate!=19000101 or  AbcTerminationDate is  null)
    and (Total_Avg is not NULL or PrevTotalAvg is not NULL)
)

Specifically, the second clause doesn’t make sense to me – it’s 2 sub-clauses separated by the OR operator seem contradictory.

The AbcTerminationDate field is declared as INT NULL in a table called Members. I believe a date of 19000101 in the system means NULL or a default value or no value, i.e. that a member is NOT terminated. So the query appears to blank out a whole lot of fields/figures if a member is marked as terminated, which would be when the AbcTerminationDate is NULL or has the default value.

Without knowing any more information, what do you make of it?

Answer 1

It does look like those are contradictory. Perhaps they meant

and !(AbcTerminationDate==19000101 or AbcTerminationDate is null)

?