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Phantom Phenomenon

 

When there are multiple transactions that are taking place at the same time in an uncontrolled or unrestricted manner, sometimes, the order of ‘select’ and ’insert/delete ’ commands may allow the database in different states. This state is called the Phantom Phenomenon.

 

Example-12 :

Consider the following statements.

 (a) Select  FName 

From  FACULTY

Where salary < 50000 ;

 (b) Insert into FACULTY values(‘111’, 22,‘CSE’,’Ramu’,’PhD’, 44000) ; 

 

Here, the order of (a) and (b) will result in different states of the database. This situation is known as ‘Phantom Phenomenon’.

 

Reference Link

Phantom Phenomenon