MySQL one to many relationship add values from one table to another

Question

I have two tables, customer and CAM (customer account manager). CAM has 30 unique entries and customer has 300. The tables should have a one to many relationship with one CAM to many customers.

The table for CAM is as follows:

create table CAM(  
    CAM_ID integer auto_increment primary key,  
    First_Name varchar(20) not null,  
    Last_Name varchar(20) not null,  
    Current_Staff boolean  
);

The table for customer is as follows

create table customer(
    reference integer auto_increment primary key,
    company_name varchar(25) not null,
    address varchar(30) not null,
    town varchar(30),
    post_code varchar(10) not null,
    telephone varchar(20) not null,
    contact_fname varchar(25),
    contact_sname varchar(25),
    contact_email varchar(40)
);

The CAM table is a new table, the customer table was pre-existing. I added in the CAM_ID column to the customer table through two different statements:
1

alter table customer
add CAM_ID int

2

alter table customer
add foreign key (CAM_ID) references CAM(CAM_ID)

When trying to run them as one query it was failing.

I need some advice on how to populate the CAM_ID column within the customer table with the values from the CAM table. I've tried some methods that ultimately didn't work. For example, I was trying to tie both the CAM_ID to the reference value, however this only populated the first 30 rows. Additionally, I tried to do some math with the values in both CAM_ID and reference to try a tie them together. Again this only tied 30 rows together, though in a different way to the first method I tried. I'm not sure if I've done something wrong with the way the foreign key has been setup.

Answer 1

When trying to run them as one query it was failing.

Proper way of combining these two DDLs:

alter table customer
add (CAM_ID int,
 foreign key (CAM_ID) references CAM(CAM_ID)
)

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