Database Interview Questions

Q.1: What is the difference between an implicit lock and explicit lock?

An implicit lock is implied but not acquired while and explicit lock is requested for a record or table, explicitly.

Q.2: What is the difference between database administrator and a data administrator?

A database administrator is a person or a group of people responsible for the accuracy, maintenance and performance of the management systems. And a data administrator is and individual or an organization responsible for specification, acquisition and maintenance of date management. It does everything from the designing, validation and security of the files and databases.

Q.3: What are the two components of an enterprise class database system between which the DBMS works?

Database application and the database.

Q.4: What is rollback and roll forward?

Rollback means undoing the changes made by a transaction. It does before anything commits to cancel and changes to a database. Roll forward on the other hand means, re doing all the changes made by a transaction after it commits or overwrites the changed value to ensure consistency.

Q.5: What is one of the components of database out of these? User data, metadata, Reports, Indexes?
It is Reports. They are used to generally summarize and present the data in the form of tables. It generally answers a particular question.
Q.6: What do you think about an enterprise resource planning application? What is it an example of?
It is an example of Multiuser database application.
Q.7: Which of the following is not considered as a basic element of an enterprise class database system?
Options – User, Databse apps, DBMS, COBOL Programs.
The answer is COBOL programs.
Q.8: How can one recover the database via reprocessing?
Reprocessing is not very feasible. If we process the transaction, it is possible that the database is safe and accessible and so reprocessing can be done. It is not preferred by many for a simple reason that it is a costly process and it requires a lot of re-work, again and again. With many transactions calling for a rollback, it becomes tedious and involves loads of re-work.
Q.9: What is normalization?
It is the way of organizing data in a database by removing unneeded and not consistent data. The database normalization has some rules to be followed while creating databases-

• First Normal form is to – remove duplicate column first and identify each set of resembling and related data with a primary key.
• Second Normal from is to – create a relationship between master and master detail tablets by using a foreign key.
• Third Normal form is to – remove the fields that are not dependent on the primary key. They are independent.

Q.10: What is de-normalization?
De-normalization is a process of optimizing the performance of a database. It is a process of combining and organizing data in a single table. It is then used to access specific data needs according to the users.
Q.11: What is the meaning of flat file database?
It is a type of database where in there are no programs or languages which can be accessed by a user. There are no cross file capabilities but it is still user friendly and provides pretty good user friendly management.