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It is also possible to specify DRI actions on UPDATE and DELETE, such as CASCADE (forwards a change/delete in the referenced table to the referencing tables), NO ACTION (if the specific row is referenced, changing the key is not allowed) or SET NULL / SET DEFAULT (a changed/deleted key in the referenced table results in setting the referencing ...
A foreign key is a set of attributes in a table that refers to the primary key of another table, linking these two tables. In the context of relational databases, a foreign key is subject to an inclusion dependency constraint that the tuples consisting of the foreign key attributes in one relation, R, must also exist in some other (not necessarily distinct) relation, S; furthermore that those ...
An SQL UPDATE statement changes the data of one or more records in a table. Either all the rows can be updated, or a subset may be chosen using a condition. The UPDATE statement has the following form: [1] UPDATE table_name SET column_name = value [, column_name = value ...] [WHERE condition]
An Oracle syntax statement trigger that is called after an UPDATE to the phone_book table. When the trigger gets called it makes an insert into phone_book_edit_history table CREATE OR REPLACE TRIGGER phone_book_history AFTER UPDATE ON phone_book BEGIN INSERT INTO phone_book_edit_history ( audit_history_id , username , modification , edit_date ...
SQL refers to Structured Query Language, a kind of language used to access, update and manipulate database. In SQL, ROLLBACK is a command that causes all data changes since the last START TRANSACTION or BEGIN to be discarded by the relational database management systems (RDBMS), so that the state of the data is "rolled back" to the way it was before those changes were made.
The clock is ticking for families hoping to send letters to Santa Claus at the North Pole this holiday season. Letters need to be postmarked by Monday, a spokesperson for the U. S. Postal Service ...
In database systems, a propagation constraint "details what should happen to a related table when we update a row or rows of a target table" (Paul Beynon-Davies, 2004, p.108). Tables are linked using primary key to foreign key relationships.
Week 12 marks the first "Byemageddon” of the NFL season in fantasy football. A season-high six teams have their bye this week: the New York Jets, Atlanta Falcons, Buffalo Bills, Cincinnati ...