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hi guys, how can i set null references when deleting a foreign key?

you can alter the constraint on the column where the foreign key reference is used to cascade the value to null

something like this:
```sql
ALTER TABLE some_table
  DROP CONSTRAINT some_constraint, 
  ADD  CONSTRAINT some_constraint FOREIGN KEY (the_key) REFERENCES another_table(the_foreign_key) ON DELETE SET NULL;
```

i dont really get the constraint part, is it mandatory?

if you want to set to null, yes... the default one is ~~`restrict` ~~ `NO ACTION` which will not allow the foreign key to be deleted

you can add multiple behaviors too for instance:
```sql
ON UPDATE CASCADE ON DELETE SET NULL -- or SET DEFAULT .. etc
```