I have two tables:

~~~pgsql
CREATE TABLE est (
  est_id serial PRIMARY KEY
, est_nom varchar(70)
);

CREATE TABLE bm (
  id serial PRIMARY KEY
, est_nom int
, nom varchar(70)
, CONSTRAINT FK_bm_est FOREIGN KEY(est_nom) REFERENCES est(est_id) ON DELETE SET NULL
);
~~~

I want to insert this data in `bm`

```
INSERT INTO bm
VALUES
(netx serial,'DAPR','leopold stotch'),
(netx serial,'LDGA','fredderik gauss'),
(netx serial,'SDCD','edward gortz')
```

Input values in column 2 are strings, corresponding to `est.est_nom`. I need the matching `est.est_id` instead.

I want to get existing values from `est.est_nom` and use them for the insert into `bm.est_id`.

If not found, first insert new rows in `est` and use the resulting serial `est_nom` for the insert into `bm`.