in my CRM I have 3 SQL tables
customer a (key custnum), contact b (key contNum), customer_contact (custnum, contnum cross reference) connecting customers to contacts.
Historically some contact imported from a previews CRM do not have any cross reference.
both customer and contact table have address, city, state,zip, phone info. table c has
I am looking SQL syntax to create cross reference records for contacts which do have same address info (address, city, state, zip as customer) and don't already have a cross reference record in table c.