Database - Introduction to SQL - Discussion

Sir how did say that answer is correct? Sir you explain shortly.

What is cascade?

Please anyone explain.

Please give the complete explanation

Whts materializes views? please explain.

Please define each term's relation with question.

Is update cascad is same as if else cascading?

Cascading means if we take action on some thing then the references will get affected automatically

Example:

Like If we update record of master table the child table record will get update .


Like if take example of trigger:
create or replace trigger cascade_update
after update of c1 on t1
for each row
begin
update t2
set c2 = :new.c1
where c2 = :old.c1;
end;
/

SQL> update t1
2 set c1 = 2
3 where c1 = 1;

1 row updated.

SQL> select * from t2;

C2
----------
2
table t2 record updated automatically.


This feature is data integrity of sql...............

In my issue I had to define some additional operations (trigger) for updating concert's table. Those operations had to modify club_name and band_name. I was unable to do it, because of reference. I couldn't modify concert and then deal with club and band tables. I couldn't also do it the other way. ON UPDATE CASCADE was the key to solve the problem.

How actually the data integrity is ensured in the cascade?