Validating constraints and oracle
JSON in Motion [November 2016] by Arup Nanda Create JSON documents by using plain SQL, text indexes for fuzzy searches, and relational views.The Power of Cloud PL/SQL [November 2016] by Steven Feuerstein Oracle Database 12 Release 2 delivers better database development to the cloud.statements, and identify the column or columns affected by the constraint and identify the conditions of the constraint.This section discusses the concepts of constraints and identifies the SQL statements used to define and manage integrity constraints.The triggering event is either a INSERT, DELETE, or UPDATE command. The trigger can be either row-level or statement-level, where the former fires once for each row affected by the triggering statement and the latter fires once for the whole statement.ALTER TABLE chicken ADD CONSTRAINT chicken REFegg FOREIGN KEY (e ID) REFERENCES egg(e ID) INITIALLY DEFERRED DEFERRABLE; ALTER TABLE egg ADD CONSTRAINT egg REFchicken FOREIGN KEY (c ID) REFERENCES chicken(c ID) INITIALLY DEFERRED DEFERRABLE; In general, Oracle returns an error message when a constraint is violated.Thus, you should always enable the constraint after completing any of the operations listed in the preceding bullet list.While a constraint is enabled, no row violating the constraint can be inserted into the table.
Sequential Additions and Different Points of View [February 2017] by Melanie Caffrey Part 7 in a second series on the basics of the relational database and SQL Long and Overflowing [February 2017] by Connor Mc Donald LISTAGG in Oracle Database 12 Release 2 solves the problem of excessively long lists.
Triggers are a special PL/SQL construct similar to procedures.
However, a procedure is executed explicitly from another block via a procedure call, while a trigger is executed implicitly whenever the triggering event happens.
Information on SQL constraints can be found in the textbook.
The Oracle implementation of constraints differs from the SQL standard, as documented in Oracle 9i SQL versus Standard SQL.