Question

Consider the following entities and relationships
Student (rollno, name, address, class)Subject (code, subjectName, teacherName)
Stud-sub (rollno, code, marks)Define a trigger before insert for every row as a student, subject table, wheneven marks entered is < 0 or > 100, Raise an application error and display corresponding message.

Answer 1

Trigger: A trigger is a stored procedure in database which automatically invokes whenever a special event in the database occurs. For example, a trigger can be invoked when a row is inserted into a specified table or when certain table columns are being updated.

Syntax:

create trigger [trigger_name]

[before | after]

{insert | update | delete}

on [table_name]

[for each row]

[trigger_body]