Q1. What is the difference between primary key and unique key?
Difference between primary key and unique key
A primary key is a table that represents each row in the table. The primary key will not allow any duplicate value or Null value. The entered value cannot be changed in a primary key.
A unique key is also a table like a primary key, but the unique key will accept one duplicate value or Null value.
Q2. What is normalization in DBMS?
Normalization in DBMS is the term used for organizing data in the database without accepting any deletion, update or insertion. 1nf, 2nf, and 3nf are some of the examples of normalization used to organize the data in different techniques.
Q3. How many types of database languages are available in DBMS?
Q4. What is data abstraction in DBMS?
Database systems are composed of complex data structures and in order to be the database with user interaction, a technique was developed to hide any internal irrelevant details from Developers or users. This process of hiding from the user is known as data abstraction. There are three basic levels of this process i.e. physical, logical and view. The main purpose of this system is to provide an abstract view to the users.
Q5. Explain what is Relational Algebra?
Relational Algebra is a query language used to get input as relation and yield output of regard in a modified form. An operator can raise the query, and the most likely operator will be unary or binary. The relational queries are performed when there is a higher level of language used to handle the questions.
Q6. What is atomicity and aggregation?
In atomicity, when an ongoing transaction is incomplete, the user does not need to worry about the incompletion. DBMS ensures to complete the action. Either the operation will be completed, or the entire system will be stopped and restarted.
When a relation to be expressed within the relationships, a system is followed to execute this process. The process is termed as aggregation.
Q7. What is functional Dependency?
Q8. What is E-R model?
Entity-Relationship modeling represents a graphical approach for database design by utilizing the entity-relationship, it depicts real-world projects. In ER modeling, the entities are modeled along with their attributes and overall relationship among entities. Also, describe the interrelated interest in any specific domain of knowledge. The basic ER model is comprised of several and its types and specifies the relationship that exists between them.
Q9. What is Object Oriented model?
Q10. What is BCNF?
BCNF (Boyce-Codd Normal Form) is a general form that is utilized in database normalization. It is the stronger version than the third normal form which was developed by Raymond and Edgar in 1974. It is based on the functional dependencies which take account of all the candidate keys in their precise relation and it also has the additional constants compared with the significant definition of 3NF. Its application may identify any additional redundancy which might be caused by the dependency to violate one or multiple candidate keys.
Q11. What is extension and intension?
Q12. What is the difference between DBMS and RDBMS?
Q13. What is a transaction?
Q14. Explain the difference between attributes and identifiers.
Q15. List few the advantages of DBMS?
Q16. What is data dictionary?
Q17. What is a query and sub query?
Q18. List few basic DDL and DML commands?
Q19. What is join? Mention its types.
Q20. Enlist various phases of transaction.
Q21. What is difference between candidate key and foreign key?
Difference between candidate key and foreign key
Candidate key - This key is a candidate for primary care for any table and it can fulfill all the requirements of the primary key which cannot be referred to as null. They have unique records for the primary key as a candidate and every table has at least one of them.
Foreign key - It is used to define the relationship between two tables. Whenever there is a need to implement a relationship between the concepts of the foreign key is used.