Local temporary table.

Add "set quoted_identifier off" as first line.

declare @cmd varchar(255)

declare @county varchar(255)

select  @county = "St.Mary's County"

select @cmd = 'INSERT  INTO Tbl_temp_stat  VALUES ("' + @county + '",460,50,0 )'

exec (@cmd)

No way, Sorry.

Use distinct.

SELECT distinct C.*

FROM Customers C INNER JOIN Orders O ON C.CustomerID = O.CustomerID

   INNER JOIN [Order Details] OD ON O.OrderID = OD.OrderID

WHERE OD.Quantity < 5

The query could involve many disk I/O, being blocked or large number records travel on the network back to the client etc.

Most likely you might have problem with your network...

The first query show customer once only who meets the your condition but second will show same customer many times if the customer made more than one orders and quantity...

You really don't have to set database in single-user mode to perform reindex and integrity check without repair. If you does find database integrity errors by run integrity check, then...

How does ArcServe 2000 backup transaction log? Does it backup and truncate the log like SQL Server command "backup log ......"? I am wondering it just backup th log but...

The number of open connections has also impacted to number of worker threads available to SQL Server processes.

When the actual number of user connections is less than the amount set...

You are right on that. I am not sure whether there are any network performance impact to the server when many connections keep open, Anyone has more comments?

Could it be some NULL records exist?

Check the ANSI NULLs setting in ODBC.

It looks like xp_sqlmaint is going to open another connection to the database but database has been set to single user mode.

Can this problem be reproduced?

Did you run dbcc checktable to the table? You may drop the function, clear out buffer by DBCC DROPCLEANBUFFERS and DBCC FREEPROCCACHE and recreate the function?