Why use triggers in SQL Server?
A trigger is a special type of stored procedure that automatically runs when an event occurs in the database server.
DML triggers run when a user tries to modify data through a data manipulation language (DML) event.
DML events are INSERT, UPDATE, or DELETE statements on a table or view..
What are three major types of constraints?
Types of constraintsNOT NULL.UNIQUE.DEFAULT.CHECK.Key Constraints – PRIMARY KEY, FOREIGN KEY.Domain constraints.Mapping constraints.
Why do we need constraints?
Constraints are necessary to develop respect for the views and beliefs of others. It is necessary for the creation of a society. Absence of constraint would lead to the imposition of beliefs and ideas of stronger groups eventually leading to conflict. Constraints are required to control violence and settle disputes.
What are constraints What is the purpose of constraints?
Constraints are used to limit the type of data that can go into a table. This ensures the accuracy and reliability of the data in the table. If there is any violation between the constraint and the data action, the action is aborted. Constraints can be column level or table level.
What are the benefits of a trigger?
Following are the benefits of triggers.Generating some derived column values automatically.Enforcing referential integrity.Event logging and storing information on table access.Auditing.Synchronous replication of tables.Imposing security authorizations.Preventing invalid transactions.
What is the difference between constraints and triggers in Oracle?
Trigger affects only those rows, which are added after it is enabled. Constraints affects all the rows i.e. the once that existed before and the ones that were newly added. A constraint is responsible only for maintaining the integrity of the database.