Dealing with constraints violation, Database Management System

Assignment Help:

If the deletion violates referential integrity constraint, then three alternatives are available:

  • Default option: - refuse the deletion. It is the job of the DBMS to describe to the user why the deletion was rejected.
  • Attempt to propagate (or cascade) the deletion by deleting tuples that reference the tuple that is being deleted.
  • Vary the value of referencing attribute that origins the violation.

Example:

Let R:

A#

B

C^

A1

B1

C1

A2

B3

C3

A3

B4

C3

A4

B1

C5

Q

C#

D

C1

D1

C3

D2

C5

D3

 

 

 

Note:

1) '#' shows the Primary key of a relation.

2) '^' shows the Foreign key of a relation.

(1) Delete a tuple with C# = 'C1' in Q.

Violated constraint: - Referential Integrity constraint

Motive: - Tuples in relation A refer to tuple in Q.

Dealing: - Options available are

1)  Decline the deletion.

2)  DBMS may automatically delete all tuples from relation S and Q with C

# = 'C1'. This is known as cascade detection.

3)  The one more option would result in putting NULL value in R where C1 exist, which is the initial tuple R in the attribute C.


Related Discussions:- Dealing with constraints violation

Horizontal Fragmentation, I want to fragment existing table using java code...

I want to fragment existing table using java code... help me..!!

Report writing help on database mgmt, Report writing help on database mgmt ...

Report writing help on database mgmt Project Description: Use of Harvard referencing, critical analysis is required. Skills required: Academic Writing, Technical Writin

Explain growing phase of locking, Explain Growing Phase of locking Grow...

Explain Growing Phase of locking Growing Phase: In this phase the transaction can only obtain locks, but cannot release any lock. The transaction enters the growing phase as so

What is de-normalization, What is De-normalization? De-normalization is...

What is De-normalization? De-normalization is the method of attempting to optimize the performance of a database by adding redundant data. It is sometimes essential because cur

Original Database, I need an ERD created for any original database(can be o...

I need an ERD created for any original database(can be on anything). It needs to be 3NF. I then need all the CREATE STATEMENTS, INSERT STATEMENTS(anything you can think of as long

Describe the static hash file with buckets and chaining, Describe the stati...

Describe the static hash file with buckets and chaining and show how insertion, deletion and modification of a record can be performed. In static hash file organization, the wo

What is a database, What is a database? At any given time, they're sto...

What is a database? At any given time, they're storing a tremendous amount of information - inventory, in the case of Amazon, messages and interrelationships in the case of Tw

Explain the static or conservative two phase locking, Explain the Static or...

Explain the Static or conservative Two Phase Locking: Static (or conservative) Two Phase Locking: In this type of scheme, all the data items are locked earlier than any opera

Explain the term- collation, What is Collation Collation is a kind of ...

What is Collation Collation is a kind of sort order. There are majorly 3 types of sort orders, namely: i.) Dictionary case insensitive ii.)Dictionary - case sensitive

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd