If foreign keys should only reference a primary key, and any other use of it is bad design, the initial objection then does not hold weight. as oracle allows foreign keys to reference a unique constraint, then there's no theoretical reason to not have on update cascade as well.. A foreign key is a way to enforce referential integrity within your oracle database. a foreign key means that values in one table must also appear in another table. the referenced table is called the parent table while the table with the foreign key is called the child table .. The handling of foreign key references to nonunique keys or keys that contain null values is not well defined for operations such as update or delete cascade. you are advised to use foreign keys that reference only unique (including primary) and not null keys..
I'm working with both oracle and sql server. and in sql, i created a foreign key with the on update cascade option. so basically, whenever i update the column in the primary key - all of the other foreign keys (in tables) will be updated too.. I defined a parent table lsu_trans_requests_t and its child table lsu_trans_resources_t each with a primary key. the table lsu_trans_resources_t has a foreign key trans_request_id which naturally holds the primary key value of the parent record.. Sql foreign key constraint. a foreign key is a key used to link two tables together. a foreign key is a field (or collection of fields) in one table that refers to the primary key in another table..
