1/15/2024 0 Comments Sqlite foreign key examples![]() The value of the parent’s unique keys cannot be changed if the update rule is RESTRICT and there are one or more dependent rows. ![]() When we insert other than the NULL value into the foreign key constraint, the value must exist in the referenced column else, a violation message occurred.We can also insert NULL values in the child table.Foreign key constraints can refer to the tables within the same database.FOREIGN KEY constraints can reference another column in the same table.Foreign key constraint does not have to be linked only to the primary key of another table it can also be linked to the UNIQUE constraint of another table.Foreign keys are not applicable to temporary tables.After deleting or updating parent data, The child data will either be deleted or updated.Ĭreating a foreign key in an existing table requires ALTER permission on the table. CASCADE- We can use this together with ON DELETE and ON UPDATE.SET NULL, NO ACTION, CASCADE, SET DEFAULT are some of the values of this parameter. ON UPDATE- This is an optional parameter that takes action on the child data after an update on the parent data. ![]()
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