Using SQL to create a 'first character' field

How would I go about creating a new field which just contains the first character (alphabetical) of another field?

Also, if the field starts with a numeric, would it be possible for the new field to have the character '0'?

For instance:

Lemons - L
Apples - A
Pears - P
12345 - 0

UPDATE Table1 SET Table1.Field2 = IIf(Val([Table1].[Field1]),0,Left([Table1].[Field1],1));

S-