PostgreSQL

Question 1

What is PostgreSQL and what are some alternative relational databases?

Answer 1

It is a relational database, and alternatives are: MySQL (also free), SQL Server by Microsoft, and Oracle by Oracle Corporation

Question 2

What are some advantages of learning a relational database?

Answer 2

Use to store related data, maximize data integrity, learn SQL language

Question 3

What is one way to see if PostgreSQL is running?

Answer 3

Run top, check status with sudo service postgresql status

Question 4

What is a database schema?

Answer 4

A collection of tables that describe how the DB should be organized

Question 5

What is a table?

Answer 5

List of rows with same attributes

Question 6

What is a row?

Answer 6

data with same attributes

Question 7

What is SQL and how is it different from languages like JavaScript?

Answer 7

structured query language capable of interacting with relational databases. Its a declarative language

Question 8

How do you retrieve specific columns from a database table?

Answer 8

select keyword

Question 9

How do you filter rows based on some specific criteria?

Answer 9

where keyword

Question 10

What are the benefits of formatting your SQL?

Answer 10

increases readability, easier to spot errors

Question 11

What are four comparison operators that can be used in a where clause?

Answer 11

=, , !=

Question 12

How do you limit the number of rows returned in a result set?

Answer 12

limit keyword

Question 13

How do you retrieve all columns from a database table?

Answer 13

*

Question 14

How do you control the sort order of a result set?

Answer 14

order by

Question 15

How do you add a row to a SQL table?

Answer 15

insert into “table name” (‘attributes’)

values (‘values’);

Question 16

What is a tuple?

Answer 16

a list of values is referred to as a tuple

Question 17

How do you add multiple rows to a SQL table at once?

Answer 17

multiple rows of values

values (‘value’),
‘value’

Question 18

How do you get back the row being inserted into a table without a separate select statement?

Answer 18

returning *;

Question 19

How do you update rows in a database table?

Answer 19

update “table name”

set “attribute” = ‘value’

Question 20

Why is it important to include a where clause in your update statements?

Answer 20

otherwise it will update all rows

Question 21

How do you delete rows from a database table?

Answer 21

delete from “table name”

Question 22

How do you accidentally delete all rows from a table?

Answer 22

By not specifying where to delete

Question 23

What is a foreign key?

Answer 23

a column that links tables

Question 24

How do you join two SQL tables?

Answer 24

2 joins

Question 25

How do you temporarily rename columns or tables in a SQL statement?

Answer 25

use “as”

Question 26

What are some examples of aggregate functions?

Answer 26

max, sum, count, avg, min

Question 27

What is the purpose of a group by clause?

Answer 27

group rows together and run aggregate functions on these groups

Question 28

What are the three states a Promise can be in?

Answer 28

pending, fulfilled, rejected

Question 29

How do you handle the fulfillment of a Promise?

Answer 29

promise.then(), which will execute if and when the promise is fulfilled

Question 30

How do you handle the rejection of a Promise?

Answer 30

promise.catch(), or then with an error handler