DATABASE | SQL | SQL INTERVIEW QUESTION AND ANSWERS 7 | WHAT ARE THE TYPES OF SQL COMMANDS? | WHAT IS AN ATTRIBUTE? | WHAT ARE THE DIFFERENT TYPES OF DATA MODELS ? | WHAT IS AN ACTIVE DATABASE? | WHAT ARE ACID PROPERTIES? | DEFINE SELF JOIN?

Sql Interview Question and Answers:

37.     What are the types of SQL Commands?
    Data Definition Language (DDL)
    Data Manipulation Language (DML)
    Data Query Language (DQL)
    Data Control Language (DCL)

38.     What is an attribute?
    An entity is represented by a set of attributes.
    Attributes are descriptive properties possessed by each member of an entity set.
    There are different types of attributes.
    Simple
    Composite
    Single-valued
    Derived

39.     What are the different types of data models ?
    Entity relationship model
    Relational model
    Hierarchical model
    Network model
    Object oriented model
    Object relational model

40.     What is an active database?
      Active database is a database that includes active rules, mostly in the form of ECA rules(Event Condition rules).
Active database systems enhance traditional database functionality with powerful rule processing cabalities, providing a uniform and efficient mechanism for database system applications

41.     What are ACID properties?
    Atomicity
    Consistency
    Isolation
    Durability

42.     Define Self Join?
      Self join means joining one table with itself.
The self join can be viewed as a join of two copies of the same table.