Course 1, Module 3

Question 1

What is SQL?

Answer 1

Just as humans use different languages to communicate with others, so do computers. Structured Query Language (or SQL, often pronounced “sequel”) enables data analysts to talk to their databases. SQL is one of the most useful data analyst tools, especially when working with large datasets in tables. It can help you investigate huge databases, track down text (referred to as strings) and numbers, and filter for the exact kind of data you need—much faster than a spreadsheet can.

Question 2

What is a query?

Answer 2

A request for data or info from a database

Question 3

In programming, what is a syntax?

Answer 3

Syntax is the predetermined structure of a language that includes all required words, symbols, and punctuation, as well as their proper placement.

Question 4

What is the syntax of every SQL query?

Answer 4

Use SELECT to choose the columns you want to return.

Use FROM to choose the tables where the columns you want are located.

Use WHERE to filter for certain information.

Question 5

Are capitalization, indentation, and semicolons required?

Answer 5

No but highly recommended for clarity and for better maintenance.

The semicolon is a statement terminator. However, not all SQL databases have adopted or enforce the semicolon. Still recommended to us it.

Question 6

What is LIKE keyword?

Answer 6

Used to search for patterns, e.g.

WHERE field1 LIKE ‘Ch%’

Here % is used as a wildcard to match one or more characters.

Question 7

How to select ALL columns in a table?

Answer 7

select *

Question 8

How to create comments?

Answer 8

/* blabla */ (not as supported)

– blabla (most suported)

Question 9

What are aliases?

Answer 9

A new name to the column or table names to make them easier to work with (and avoid the need for comments). This is done with a SQL AS clause, e.g.

FROM
actual_table_name AS my_table_alias

Question 10

What is non equal sign in SQL?

Answer 10

<>

Question 11

What are the steps to plan a data visualization?

Answer 11

Step 1: Explore the data for patterns

Step 2: Plan your visuals, i.e. what should they describe (e.g. sales number over time)

Step 3: Create your visuals. A mix of different visuals will best communicate your findings and turn your analysis into the most compelling story for stakeholders.

Each type of chart has a specific use. E.g. A line chart would be the most appropriate visualization when showing the change in someone’s salary over time.

Basic visualization tools include Google Sheets and more powerful tools include Tableau and RStudio.