Postgresql - change foreign key to another column

I have two tables:

create table test1 (
oldPrimaryKey varchar(100) primary key, 
someText varchar(100)
)

create table test2 (
someText varchar(100),
 oldPrimaryKey varchar(100) references test1(oldPrimaryKey)
)

I need to change oldPrimaryKey to new one so I do this:

1. Drop old one key:

   • alter table test1 drop constraint test1_pkey;
   • alter table test2 drop constraint test2_oldprimarykey_fkey;

2. Create new column:

   • alter table test1 add column newPrimaryKey bigint;
3. Populate it using sequence:
   • create sequence add_id_seq start with 1 increment by 1 cache 1;
   • update test1 set newPrimaryKey = nextval('add_id_seq');
4. Change “newPrimaryKey” column to be primary key:
   • alter table test1 add constraint keyName primary key(newPrimaryKey);

Now I have something like this:

CREATE TABLE test1
(
  oldprimarykey character varying(100) NOT NULL,
  sometext character varying(100),
  newprimarykey bigint NOT NULL,
  CONSTRAINT keyname PRIMARY KEY (newprimarykey)
)

CREATE TABLE test2
(
  sometext character varying(100),
  oldprimarykey character varying(100),
  CONSTRAINT test2_oldprimarykey_fkey FOREIGN KEY (oldprimarykey)
      REFERENCES test1 (oldprimarykey) MATCH SIMPLE
      ON UPDATE NO ACTION ON DELETE NO ACTION
)

I don’t know what to do now (some script?). I need to change value from table test2 column oldprimarykey to corresponding value from table test1 column newprimarykey.

If it is too chaotic I will try to give an example of the normal data:

Rows from table1 (oldprimarykey, sometext, newprimarykey):

1. [email protected], ‘some text’, 1
2. [email protected], ‘more text’, 2

Corresponding rows from table2 (sometext, oldprimarykey):

1. ‘some text’, [email protected]
2. ‘text text’, test2test.com

I want to change email adress from table2 to corresponding int from table1.