Concept explainers
Explanation of Solution
Trigger:
The trigger is a named set of SQL statement that is executed at the time of data modification or meets some data description.
- If the stated when trigger condition meets up, then the mentioned action in the trigger has been performed.
A trigger contains three parts and they are explained as shown below:
Event:
It specifies the change to be made, such as an UPDATE or DELETE of a record.
Condition:
It specifies the condition to examine the records about to be affected. For each record, that meets the condition given in the trigger.
Action:
The action performed after the start of the trigger.
The syntax to create a trigger is as given below:
CREATE TRIGGER trigger_name
{BEFORE| AFTER|INSTEAD OF} {INSERT|DELETE|UPDATE} ON
table_name
[FOR EACH{ROW|STATEMENT}] [WHEN(condition)]
<triggered SQL statement here>;
Purpose of trigger:
The purpose of trigger is given below:
- For enforcement of business or security constraints...
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Database Systems: Design, Implementation, & Management
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- A Guide to SQLComputer ScienceISBN:9781111527273Author:Philip J. PrattPublisher:Course Technology Ptr