Oracle DBMS Interview Question and Answers

13. What are the types of normalization?
  There are six different normal forms, which are given as follows:
  • First Normal Form (1NF) – A relation R is in 1NF if and only if all the underlying domains contain atomic values only.
  • Second Normal Form (2NF) – A relation R is in 2NF if and only if it is in 1NF and every non key attribute is fully functionally dependent on the primary key.
  • Third Normal Form (3NF) – A relation R is in 3NF if and only if it is in 2NF and every non key attribute is non transitively dependent on the primary key.
  • Boyce Codd Normal Form (BCNF) – A relation R is in BCNF if and only if every determinant is a candidate key.
  • Fourth Normal Form (4 NF) – A relation R is in 4NF if and only if there exists multi valued dependency in R, say A >> B, then, all the attributes of R are also functionally dependent on A.
  • Fifth Normal Form ( 5 NF) – A relation R is in 5NF or Project Join Normal Form (PJNF) if and only if every join dependency is implied by candidate keys.
 
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14. Which sorting algorithm does Oracle follow?
 
  • Oracle used to follow a balanced binary tree sorting algorithm to effectively build an in memory index on the incoming data.
  • Binary tree search places a huge memory and CPU overhead on the system for large searches; therefore, Oracle introduced an algorithm based on heap sort, which is more efficient.
  • However, it also has a limitation of re ordering incoming rows even when the data is not arriving out of order.
 
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15. How is Oracle different from other programming languages?
  Oracle or any other DBMS is a program that handles user requests (data retrieval, storage or modification requests) without any requirement to specify the algorithm to do so.
 
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16. What other storage systems are available?
 
  • Oracle is a type of Relational Database Management System (RDBMS).
  • Another available storgae system is Hierarchical Storage Management system, such as Information Management System (IMS) from IDM and Integrated Database Management System (IDMS) from Compute Associates.
 
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