CODEWITHSUNDEEP
postgresqlforeign-keysddl
ldrg
ldrg

Reputation: 4511

Adding a NOT VALID foreign key in Postgres

Example schema: http://sqlfiddle.com/#!1/3d410

I've already got a table and I want to add a new, not valid foreign key to the table. What's the correct syntax for adding a NOT VALID foreign key?

CREATE TABLE junks (
  id serial PRIMARY KEY,
  name text
);

CREATE TABLE trunks (
  id serial PRIMARY KEY,
  name text
  -- no fk
);

-- and the below does not work!

--ALTER TABLE trunks ADD junk serial REFERENCES junks(id) NOT VALID;

Upvotes: 1

Views: 5576

Answers (2)

Robert Rohm
Robert Rohm

Reputation: 341

This works: 

ALTER TABLE trunks ADD CONSTRAINT FK_junk_id 
  FOREIGN KEY (id) 
  REFERENCES junks(id) 
  NOT VALID
;

See, e.g.: http://www.postgresql.org/docs/devel/static/ddl-alter.html#AEN2758

Upvotes: 1

Clodoaldo Neto
Clodoaldo Neto

Reputation: 125524

You first add the column:

alter table trunks add column junk serial;

Then add the constraint to the table:

alter table trunks add constraint the_constraint_name
    FOREIGN KEY (junk)
    REFERENCES junks (id)
    not valid;

Upvotes: 4

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