Data Analysis and SQL Basics Quiz

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Questions and Answers

What type of analysis focuses on how data changes over a specific time period?

Qualitative analysis

Comparative analysis

Trend analysis (correct)

Descriptive analysis

Which data source offers information on demographics, economy, and society in Spain?

Central Statistics Office

Economic Research Council

National Institute of Statistics (INE) (correct)

Stock Exchange Authority

Which of the following is NOT an aspect of the data provided by INE?

Labor market survey data

Societal living conditions data

Demography and population statistics

Survey on Consumer Behavior (correct)

What type of analysis is used to compare data between different regions or groups?

Comparative analysis Signup and view all the answers

Which ministry in Spain provides a range of financial data and statistics?

Ministry of Economy, Trade and Enterprise Signup and view all the answers

Which operator is used for pattern matching in strings?

LIKE Signup and view all the answers

What does the function LENGTH do in SQL?

Returns the number of characters in a string Signup and view all the answers

Which of the following SQL statements uses a logical operator?

SELECT * FROM rentals WHERE NOT (returndate IS NULL) Signup and view all the answers

What is the purpose of a subquery in SQL?

To break down complex queries into simpler, nested queries Signup and view all the answers

What does the function TRIM do in SQL?

Removes spaces from both ends of a string Signup and view all the answers

What is the primary definition of 'Velocity' in the context of Big Data?

The speed at which data is created and processed Signup and view all the answers

Which of the following is NOT one of the 5 Vs of Big Data?

Visualization Signup and view all the answers

What percentage of global data is stored in Relational Databases?

Less than 20% Signup and view all the answers

What is the primary characteristic of Data Lakes?

They maintain data in a raw format without transformation Signup and view all the answers

What is a common use of HDFS (Hadoop Distributed File System)?

To handle large volumes of unstructured or semi-structured data Signup and view all the answers

Which platform generates the highest number of posts per minute?

Instagram Signup and view all the answers

Which of these best describes the concept of 'Veracity' in Big Data?

The accuracy and reliability of the data collected Signup and view all the answers

What amount of data is expected to be generated globally by 2025?

175 zettabytes Signup and view all the answers

What types of relationships does Excel support?

One-to-one and one-to-many relationships Signup and view all the answers

Which method can help maintain data integrity in Excel?

Implementing validation rules Signup and view all the answers

What is the main purpose of normalization in databases?

To minimize redundancy and improve data integrity Signup and view all the answers

Which function can be used in Excel to simulate a basic JOIN operation in SQL?

VLOOKUP Signup and view all the answers

What is one limitation of VLOOKUP in Excel?

It requires sorted data or only exact matches Signup and view all the answers

Which technique does NOT relate to basic normalization in Excel?

Storing all data in a single spreadsheet Signup and view all the answers

Why is referential integrity not enforced in Excel relationships?

Manual attention to data consistency is necessary Signup and view all the answers

What feature can be used in Excel to highlight potential errors in data?

Conditional Formatting Signup and view all the answers

What does the subquery `SELECT customerid FROM rentals ORDER BY totalcost DESC LIMIT 1` accomplish?

Identifies the customer who has rented the most expensive car. Signup and view all the answers

In the query `SELECT carid FROM rentals WHERE customerid IN (SELECT customerid FROM rentals GROUP BY customerid HAVING COUNT(*) > 1)`, what is being retrieved?

Cars rented by customers who have rented more than twice. Signup and view all the answers

Which of the following best describes the purpose of a correlated subquery?

To retrieve information based on a value from another row in the outer query. Signup and view all the answers

What is a primary limitation of using Excel as a flat-file database?

It lacks complex relational structures and integrity constraints. Signup and view all the answers

Which function of Excel's Data Model allows users to analyze related data?

Creating relationships between tables. Signup and view all the answers

What does the `SELECT total_amount FROM Orders WHERE Orders.customer_id = Customers.customer_id` subquery calculate?

Total spending for each customer. Signup and view all the answers

What is the main advantage of using a flat-file database like Excel?

It is ideal for managing small datasets without complex relationships. Signup and view all the answers

Which of the following queries selects employees with a salary above the average salary of their department?

SELECT first_name, salary FROM Employees e1 WHERE salary > (SELECT AVG(salary) FROM Employees e2 WHERE e2.department = e1.department); Signup and view all the answers

What is a key feature of PowerBI Desktop?

It is free for personal use. Signup and view all the answers

How does PowerBI Service differ from PowerBI Desktop?

It is focused on sharing and collaboration. Signup and view all the answers

Which of the following statements accurately describes relational databases?

Data is organized in tables with rows and columns. Signup and view all the answers

What is NOT a primary use of PowerBI?

Storing large volumes of raw data. Signup and view all the answers

What role does AI play in Power Apps?

To assist in quickly generating database tables and forms. Signup and view all the answers

What technology does Neo4j AuraDB utilize?

Fully managed graph database service. Signup and view all the answers

What feature is a crucial aspect of the data analysis conducted using PowerBI?

Interactive dashboards for data visualization. Signup and view all the answers

Which step is NOT included in building an app with Power Apps?

Create a database structure using manual coding. Signup and view all the answers

Study Notes

Big Data

Data is crucial for decision-making in all business aspects
In 2025, the world is predicted to generate 175 zettabytes (ZB) of data (1 ZB = 1 billion gigabytes)
Daily internet user data generation is around 2.5 million gigabytes
90% of all data was generated in the past 2 years

5Vs of Big Data

Velocity: Batch, near real-time, real-time, and streaming data
Variety: Structured, unstructured, and semi-structured data
Volume: Terabytes, petabytes, and zettabytes of data
Veracity: Dependability, authenticity, source, and reputation
Value: Statistical analysis, links, correlations, and potential value

Sources of Data

Facebook
Twitter (500,000 tweets per minute)
Instagram (347,222 posts per minute)
IoT devices (75 million connected devices producing data) - sensors

Data Storage

Less than 20% of global data is stored in relational databases
80% of global data is unstructured (text, images, and videos)
Big Data Architectures, cloud storage, and NoSQL databases are used

Data Storage in HDFS

Data is divided into blocks (128 MB or 256 MB)
Distributed across multiple servers
Provides redundancy (data copies) for fault tolerance

Data Lakes

Centralized repository for diverse data (structured, semi-structured, and unstructured)
Stores raw data without transformation
Suitable for long-term analysis, where the type of analysis isn't known yet

Economic and Financial Data Sources

INE: Statistical data on economic, demographic, and social aspects (reports, databases, interactive tools)
Ministry of Economy, Trade, and Enterprise: Data on the Spanish economy, public finances, labor market, and trade balance
Spanish Government: Statistics, and data
Madrid Stock Market: Market interest rate statistics
European Statistical Office (EUROSTAT): High-quality statistics
World Bank: Data on global development
International Monetary Fund (IMF): Data on macroeconomic and financial aspects

Introduction to Databases

Databases are crucial for efficient data management across various industries
E-commerce platforms, social media, banking, healthcare, and education use databases
Before databases, data was stored using paper, magnetic tapes, books, etc. This was limited in terms of search, integrity, and scalability

Evolution of Databases

1970s: Entity-Relationship (ER) Model introduced
1980s: Relational Database Management Systems (RDBMSs) like Oracle and DBMS/SQL were introduced
1990s: NoSQL databases and data mining emerged

Basic Concepts of Databases

Databases organize related data into tables of rows and columns
Tables contain data about people, products, orders, etc.
Relationships connect tables for complex queries

SQL (Structured Query Language)

Common language for managing and manipulating relational databases
Database interaction is standardized
Queries for data retrieval, insertion, update, and deletion are possible

Main Data Types in SQL

INT: Whole Numbers (e.g., 42)
FLOAT: Floating-point numbers (3.14)
DOUBLE: Double-precision floating-point numbers (2.71828)
DECIMAL (p, s): Fixed-point numbers with precision and scale (e.g., 123.45)
VARCHAR (n): Variable-length text (e.g., "John Doe")
CHAR (n): Fixed-length text (e.g., 'A')
TEXT: Large amounts of text
DATE: Date values (e.g., 2024-07-09)
TIME: Time values (e.g., 14:30:00)
DATETIME: Date and time values (2024-07-09, 14:30:00)
TIMESTAMP: Automatically updated date and time values
BLOB: Binary Large Object (e.g., binary data)
BOOLEAN: True/False values (TRUE or FALSE)

Subqueries in SQL

Queries nested inside another query
Used to get more complex results from databases
Used in SELECT, FROM, WHERE, HAVING clauses
Retrieves the names of customers who have rented the most expensive car and other examples

Using Microsoft Excel as a Database

Excel works as a flat-file database for smaller datasets
It manages data in a single table
Relationships for analyzing related data are possible

NoSQL Databases

Non-relational databases (schema-less)
Handle diverse data types (structured, semi-structured, unstructured)
Suitable for big data and scalability

Document Stores

Stores data as documents (e.g., JSON)
Documents in the same collection can have diverse fields and structures
Useful for flexible schemas and varied data
Example use is storing articles on a news website with details like title, body, author, tags, and date

Graph Databases

Represent data as nodes connected by relationships
Efficient for scenarios with complex relationships, such as social networks, recommendations, and IT operations
Example use is social media for connecting friends, messages, and liking

Neo4j Products

Neo4j Desktop: Development environment for Neo4j databases
Neo4j Bloom: Graph visualization and exploration tool
Neo4j Graph Data Science Library: Algorithms for data analysis
Neo4j AuraDB: Fully managed graph database hosted on Google Cloud Platform (GCP)

PowerBI as a Database Tool

PowerBI Desktop: Personal use. For reports and dashboards
PowerBI Service: Cloud-based platform for collaboration (less functionalities)

Relational Databases

Data organized in tables with rows and columns
Tables are related, allowing complex queries

Normalization

Process of structuring data for optimal performance in relational databases
Organizes data to avoid data redundancy and maintain accuracy

Database Design

Process of creating a database structure for storing and retrieving data
Includes defining tables, fields, data types, and relationships for data organization and efficiency.

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Description

Test your knowledge on various types of data analysis and SQL functions in this informative quiz. Questions cover topics such as demographic data in Spain, pattern matching, and the characteristics of Big Data. Perfect for anyone looking to strengthen their understanding of data science concepts!