postgreSQL

Question 1

What is PostgreSQL and what are some alternative relational databases?

Answer 1

PostgreSQL is a powerful, free, open source Relational Database Management System (RDBMS).
alternatives: SQLite, MySQL, SQL Server by Microsoft, and Oracle by Oracle Corporation.

Question 2

What are some advantages of learning a relational database?

Answer 2

• they support good guarantees about data integrity

- store and modify data in a way that makes data corruption as unlikely as possible

Question 3

What is one way to see if PostgreSQL is running?

Answer 3

sudo service postgresql status

Question 4

What is a database schema?

Answer 4

A collection of tables and it defines how the data in a relational database should be organized

Question 5

What is a table?

Answer 5

a collection of rows that have the same attribute

Question 6

What is a row?

Answer 6

a single record in a table

Question 7

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

Answer 7

Structured Query Language (SQL) lets you access and manipulate databases. it is a declarative language while javascript is imperative

Question 8

How do you retrieve specific columns from a database table?

Answer 8

select “columnName1”, “columnName2”, …

Question 9

How do you filter rows based on some specific criteria?

Answer 9

where clause

Question 10

What are the benefits of formatting your SQL?

Answer 10

easier to read

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 clause

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 clause

Question 15

How do you add a row to a SQL table?

Answer 15

insert statement

Question 16

What is a tuple?

Answer 16

a list of values

Question 17

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

Answer 17

separate tuples by commas

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 statement

Question 20

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

Answer 20

if you don’t, you will update everything

Question 21

How do you delete rows from a database table?

Answer 21

delete statement

Question 22

How do you accidentally delete all rows from a table?

Answer 22

if you don’t have a where clause

Question 23

What is a foreign key?

Answer 23

the value of a column that refers to another column

Question 24

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

Answer 24

as clause

Question 25

What are some examples of aggregate functions?

Answer 25

sum, avg, count

Question 26

What is the purpose of a group by clause?

Answer 26

The GROUP BY clause is a SQL command that is used to group rows that have the same values.