adding event in 2nd table??

[Prasad Mhatre]

Dear Friends,

I am having 2 tables as follow:

Table 1----->     customer_id | contacts | etc this table has unique 
customer_id while Table 2 may have more than 2 records with the same customer_id
Table 2----->     customer_id | visit_no | details of visit 

I want to know an example of updating the Table 2 with autoincrementing the 
visit_no respective to the customer_id

e.g.

Table 1
customer_id | contacts | etc 
        1001       tel. nos.    etc.
        1002       tel. nos.    etc.
        1003       tel. nos.    etc.

Table 2
customer_id | visit_no | details of visit 
        1001          1          details
        1001          2          details
        1001          3          details
        1002          1          details
        1002          2          details
        1003          1          details
        1003          2          details
        1003          3          details
        1003          4          details

Can anyone suggest an example for this type of table? or someother way of 
having the same results.
At present I can update the records in 2nd table by manually entering visit_no 
value, but one has to remember the previous visit.

Any help is appreciated.

Thanks
Love and regards
Prasad