Introduction to Oracle SQL

Question 1

Definition of a database

Answer 1

Set of data stored in a computer, usually structured in a way that makes data easily accessible.

Question 2

RDBMS

Answer 2

Relational database management system is a program that allows you to create, update, and administer a relational database.

Most RDBMSs use the SQL language to access the database.

Question 3

Relational database

Answer 3

is based on the relational model of data

Question 4

PL/SQL

Answer 4

Procedural Language/SQL, or Oracle SQL, is Oracle’s implementation of SQL.

Question 5

Advantages to Oracle SQL

Answer 5

It is great for working with large databases, easy to use, has well-written documentation, and supports amazing new features.

Question 6

Disadvantages

Answer 6

Not open source

Question 7

ERD

Answer 7

An ERD is a graphical representation of the relationships among different entities.

can help you model a real-world system

Question 8

Entities

Answer 8

The entities are the things that form the basis of the real-world system and are transformed into tables in a database. This example ERD shows six entities and the relationships between them. (Customer, Invoice, InvoiceLine, Genre, Track, Album).

Question 9

Relationship between two entities with example

Answer 9

A relationship between two entities signifies that they are associated with each other. For example, a track belongs to a certain album.

Question 10

Attributes of Entity

Answer 10

Once you have established the entities and their relationships, you can enhance your ERD by adding attributes to each entity. For example, for each customer you might want to track the customer’s first and last name as well as contact information such as their address.

Question 11

SQL

Answer 11

Structured Queried Language

industry-standard language that can be used to create databases, store data, change and analyze data, and get data back out.

Question 12

Avoiding Duplicates

Answer 12

Use DISTINCT

Question 13

Linking Columns

Answer 13

CONCATENATION

Question 14

Comparison Operators

Answer 14

> , >=. <, <=, =, <>

Question 15

Comparison keywords

Answer 15

BETWEEN, IN, LIKE

Question 16

BETWEEN

Answer 16

Comparision keyword

SELECT Name, Milliseconds
FROM Track
WHERE Milliseconds BETWEEN 100000 AND 200000

Question 17

IN

Answer 17

Comparison Keyword
To look for values in a list of values.

SELECT …
FROM …
WHERE EmployeeID IN (4, 5, 6)

Question 18

LIKE

Answer 18

Compartision Keyword
When you don’t always know the exact value to search for

%
_

WHERE LastName LIKE ‘_a%’

Question 19

LIKE %, _

Answer 19

% Represents any sequence of zero or more characters
_ Represents any single character