sql update

I am trying to run an interactive SQL to update a field in a file with
the value from the same field, from another record in the same file,
based on common customer numbers.  Here is an example.

Customer
Cust#    Company       Customer_Store
17201111    1             C001111
17201111    2
17202222    1             C002222
17202222    2 

I want to update a range of customer numbers and take the Customer_Store
for Company 1 and put that store number in the same customer number for
Company 2, minus the leading 'C'.  So my file would look like this, once
my successful sql runs.

Customer
Cust#    Company       Customer_Store
17201111    1             C001111
17201111    2              001111
17202222    1             C002222
17202222    2              002222

Fields Cust# and Company are Zoned and Customer_Store is Char.

TIA for any assistance.

Sheri