Description
Hello,
When creating the recipe_ingredients table in the Many-to-Many Relationships section we currently use ON DELETE NO ACTION in the column that reference the recipes' table primary key, and in the column that references the ingredients' table primary key. Also, in that same section it is stated that
We don't want to cascade deletes because that could delete recipes and ingredients unintentionally
I don't think that's correct since, as is explained in section 5.4.5 Foreign Keys of PostgreSQL's (version 14) documentation,
CASCADE specifies that when a referenced row is deleted, row(s) referencing it should be automatically deleted as well
Based on that documentation we can conclude that using ON DELETE CASCADE on the recipe_id and ingredient_id columns of the recipe_ingredients table would only produce that, when either a referenced recipe or ingredient is deleted, the corresponding record in the recipe_ingredients table would be deleted as well. But deleting an record in the recipe_ingredients table would not delete records in either the recipes or ingredients tables.
Assuming the explanation in the paragraph above is true, it's more semantically appropriate to use ON DELETE CASCADE. For example, we wouldn't want to keep the records specifying which ingredientes are used in a recipe if we no longer have that recipe in our database (however, we can and should keep the records of the ingredients themselves since these could be used in recipes other than the one deleted).