Oracle DBMS Interview Question and Answers

1. What is database?
 
  • Databse is a structure that stores information about multiple types of entities, the attributes (or characteristics) of the entities, and the relationships among the entities.
  • It also contains data types for attributes and indexes.
 
Your Name Your Email-ID
Your Answer
2. Define Database Management System (DBMS) and RDBMS?
 
  • DBMS is a program that defines the rules for data storage and retrieval.
  • RDBMS is a special type of DBMS that stores the data in the relational format as described in the relational theory by E.F. Codd.
 
Your Name Your Email-ID
Your Answer
3. Define relationships?
 
  • A relationship is an association between entities (or tables).
  • It is based on having common data values in the designated columns of each table.
  • A relationship is defined by linking the common columns in the two tables.
  • Relationships are actual objects in the database.
Following are the three types of relationships:
  • One to one : Implies that a single records from the first table can be linked to multiple records in the second table and vice versa.
  • One to many: Implies that a single record form the first table can be linked to multiple records in the second table while a single record in the second table relates to only a single record in the first table.
  • Many to many: Implies that multiple records from the first table can be linked to multiple records in the second table and vice versa.
 
Your Name Your Email-ID
Your Answer
4. What is a primary key?
  A primary key is an attribute (or a collection of attributes) that uniquely identifies each row in the table. In other words, each entity instance in a table must be unique; and therefore, primary key is a way of ensuring this.
 
Your Name Your Email-ID
Your Answer
12345 Page 1 of 5