Question

I am moving old project that used single table inheritance in to a new database, which is more structured. How would I write a SQL script to port this?

Old structure

I’ve simplified the SQL for legibility.

CREATE TABLE customers (
  id int(11),
  ...
  firstName varchar(50),
  surname varchar(50),

  address1 varchar(50),
  address2 varchar(50),
  town varchar(50),
  county varchar(50),
  postcode varchar(50),
  country varchar(50),

  delAddress1 varchar(50),
  delAddress2 varchar(50),
  delTown varchar(50),
  delCounty varchar(50),
  delPostcode varchar(50),
  delCountry varchar(50),

  tel varchar(50),
  mobile varchar(50),
  workTel varchar(50),
);

New structure

CREATE TABLE users (
  id int(11),
  firstName varchar(50),
  surname varchar(50),
  ...
);

CREATE TABLE addresses (
  id int(11),

  ForeignKey(user),
  street1 varchar(50),
  street2 varchar(50),
  town varchar(50),
  county varchar(50),
  postcode varchar(50),
  country varchar(50),
  type ...,
);

CREATE TABLE phone_numbers (
  id int(11),
  ForeignKey(user),
  number varchar(50),
  type ...,
);

Answer 1

With appropriate cross-database notations for table references if appropriate:

INSERT INTO Users(id, firstname, surname, ...)
    SELECT id, firstname, surname, ...
        FROM Customers;
INSERT INTO Addresses(id, street1, street2, ...)
    SELECT id, street1, street2, ...
        FROM Customers;
INSERT INTO Phone_Numbers(id, number, type, ...)
    SELECT id, phone, type, ...
        FROM Customers;

If you want both the new and the old address (del* version), then repeat the address operation on the two sets of source columns with appropriate tagging. Similarly, for the three phone numbers, repeat the phone number operation. Or use a UNION in each case.