I am using an INSERT INTO .... SELECT .... type SQL command, which works 
fine from a query within Access, but doesn't work when I try to execute is 
through an OleDBCommand in  my VB2005 project.
The problem is that the value for one of the fields is calculated from an 
aggregate function which may be Null. I got around this in Access using the 
Nz function something like this:

.... SELECT NZ(Max(Field))+1 ...

but I soon found that Nz cannot be used via OleDb.
For SQL Server I think I can use something like ISNull(Max(Field),0) but 
this doesn't seem to work with Access.
I found a website that suggests using something like this instead of 
Nz(Value):

IIF(ISNull(Value),0,Value)

but I am concerned that if I replace Value with Max(Field) this will 
evalulate the Max function twice, and have an impact on performance. Is this 
a problem? and if so, is there a better way to do this?

TIA
Phil