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I cannot seem to get this right, I am trying to modify a field to be a foreign key, with cascading delete... what am i doing wrong?
ALTER TABLE my_table ADD CONSTRAINT $4 FOREIGN KEY my_field REFERENCES my_foreign_table ON DELETE CASCADE; 
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Constraints are the rules enforced on data columns on table. These are used to prevent invalid data from being entered into the database. This ensures the accuracy and reliability of the data in the database. Constraints could be column level or table level.
To find the name of a constraint in PostgreSQL, use the view pg_constraint in the pg_catalog schema. Join the view pg_catalog. pg_constraint with the view pg_class ( JOIN pg_class t ON t. oid = c.
SELECT conname FROM pg_constraint WHERE conrelid = (SELECT oid FROM pg_class WHERE relname LIKE 'tableName'); Also you can get it from pgAdmin in objects tree.
It would help if you posted the error message. But I think you are just missing the parenthesis:
ALTER TABLE my_table ADD CONSTRAINT my_fk FOREIGN KEY (my_field) REFERENCES my_foreign_table ON DELETE CASCADE; If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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