Terms

Question 1

Full Functional Dependency

Answer 1

A functional dependency X -> Y is a full functional dependency if removal of any attribute type A from X means that the dependency does not hold anymore.

Question 2

Prime Attribute

Answer 2

Add Prime

Question 3

Elementary Prime Attribute

Answer 3

Add El Prime

Question 4

Multi-valued Dependency

Answer 4

If each X value in X->->Y exactly determines a set of Y values, independently of the other attribute types.

Question 5

Join Dependency

Answer 5

Add Join

Question 6

Partial Functional Dependency

Answer 6

A functional dependency X -> Y is a partial dependency if an attribute type A from X can be removed from X and the dependency still holds.

Question 7

Transitive Dependency

Answer 7

A functional dependency where there is a set of attribute types Z that is neither a candidate key nor a subset of any key of R, and both X->Z and Z->Y hold.

Question 8

Trivial Functional Dependency

Answer 8

A functional dependency X->Y, where Y is a subset of X

Question 9

What is SQL

Answer 9

A standard language which stands for Structured Query Language

Question 10

What does SQL do

Answer 10

SQL is the core of the relational database which is used for accessing and managing a database

Question 11

What is MySQL

Answer 11

A database management system

Question 12

DDL

Answer 12

Data Definition Language - A subset of SQL that allows you to perform various operations on the database such as CREATE, ALTER, and DELETE objects.

Question 13

DML

Answer 13

Data Manipulation Language - A subset of SQL that allows you to access and manipulate data. It helps you to insert, update, delete and retrieve data from the database.

Question 14

DCL

Answer 14

Data Control Language - A subset of SQL that allows you to control access to the database. Example – Grant, Revoke access permissions.

Question 15

DBMS

Answer 15

Database Management System - a software application that interacts with the user, applications, and the database itself to capture and analyze data.

A DBMS allows a user to interact with the database. The data stored in the database can be modified, retrieved and deleted and can be of any type like strings, numbers, images, etc.

Question 16

Database

Answer 16

A structured collection of data

Question 17

Types of DBMS

Answer 17

1. Relational

2. Non-relational

Question 18

Relational DBMS

Answer 18

The data is stored in relations (tables). Example – MySQL.

Question 19

Non-relational DBMS

Answer 19

There is no concept of relations, tuples and attributes. Example – MongoDB

Question 20

What is a table?

Answer 20

A table refers to a collection of data in an organised manner in form of rows and columns.

Question 21

What is a field?

Answer 21

Refers to the number of columns in a table.

Question 22

Char vs Varchar

Answer 22

Char is fixed length ex char(10).

Varchar is variable length ex varchar(10) can store 2, 4, 5, 8 etc.

Question 23

What are constraints

Answer 23

Constraints in SQL are used to specify the limit on the data type of the table. It can be specified while creating or altering the table statement. The sample of constraints are:

NOT NULL
CHECK
DEFAULT
UNIQUE
PRIMARY KEY
FOREIGN KEY

Question 24

Data Integrity

Answer 24

defines the accuracy as well as the consistency of the data stored in a database.
It also defines integrity constraints to enforce business rules on the data when it is entered into an application or a database.

Question 25

Clustered Index

Answer 25

Used for easy retrieval of data from the database and its faster than non-clustered

Alters the way records are stored in a database as it sorts out rows by the column which is set to be clustered index

One table can only have one clustered index

Question 26

Non-clustered Index

Answer 26

Reading from non-clustered index is slower than clustered index

Does not alter the way it was stored but it creates a separate object within a table which points back to the original table rows after searching.

A table can have many non clustered index.

Question 27

Entity

Answer 27

A person, place, or thing in the real world about which data can be stored in a database. Tables store data that represents one type of entity. For example – A bank database has a customer table to store customer information. The customer table stores this information as a set of attributes (columns within the table) for each customer.

Question 28

Relationship

Answer 28

Relation or links between entities that have something to do with each other. For example – The customer name is related to the customer account number and contact information, which might be in the same table. There can also be relationships between separate tables (for example, customer to accounts).

Question 29

Index

Answer 29

Refers to a performance tuning method of allowing faster retrieval of records from the table. An index creates an entry for each value and hence it will be faster to retrieve data.

Question 30

Unique Index

Answer 30

This index does not allow the field to have duplicate values if the column is unique indexed. If a primary key is defined, a unique index can be applied automatically.

Question 31

Trigger

Answer 31

a special type of stored procedures that are defined to execute automatically in place or after data modifications. It allows you to execute a batch of code when an insert, update or any other query is executed against a specific table.

Question 32

Types of Operators

Answer 32

1. Arithmetic
2. Logical
3. Comparison

Question 33

NULL value

Answer 33

NULL value represents a value which is unavailable, unknown, assigned or not applicable whereas a zero is a number and blank space is a character.

Question 34

Subquery

Answer 34

A subquery is a query inside another query where a query is defined to retrieve data or information back from the database. In a subquery, the outer query is called as the main query whereas the inner query is called subquery. Subqueries are always executed first and the result of the subquery is passed on to the main query. It can be nested inside a SELECT, UPDATE or any other query. A subquery can also use any comparison operators such as >,< or =.