postgres

Question 1

What is PostgreSQL and what are some alternative relational databases?

Answer 1

relational database management system.
alternative relational databases: SQLite, SQLserver, SQLoracle, mySQL

Question 2

What are some advantages of learning a relational database?

Answer 2

it is widely used

Question 3

What is one way to see if PostgreSQL is running?

Answer 3

by using ‘sudo service postgresql status’ in the terminal

Question 4

What is a database schema?

Answer 4

Defines how the data in a relational database should be organized

schema defines the STRUCTURE
how you want to structure and store our data

Question 5

What is a table?

Answer 5

A table is a list of rows each having the same set of attributes
attribute - same datatypes

Question 6

What is a row?

Answer 6

having the same set of attributes
data in the table

Question 7

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

Answer 7

structured query language. a powerful way of retrieving, creating, and manipulating data

it’s a declarative programming language whereas JS is imperative

Question 8

How do you retrieve specific columns from a database table?

Answer 8

using `select “columnName”

Question 9

How do you filter rows based on some specific criteria?

Answer 9

where “columnName” = ‘thing you want’

Question 10

What are the benefits of formatting your SQL?

Answer 10

helps to make the queries more readable and easy to understand

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

using limit

Question 13

How do you retrieve all columns from a database table?

Answer 13

using select *

Question 14

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

Answer 14

order by ___ desc

Question 15

How do you add a row to a SQL table?

Answer 15

insert into “ “ (“ “, “ “)
values (‘ ‘, ‘ ‘)

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

set another ( ) with values inside it

Question 18

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

Answer 18

by putting returning *;

Question 19

How do you delete rows from a database table?

Answer 19

delete from “ “
where “ “ =
returning *;

Question 20

How do you accidentally delete all rows from a table?

Answer 20

when you just write delete from " " without any where clause

Question 21

How do you update rows in a database table?

Answer 21

update “ “
set “ “ = ___ ,
“ “ = ____
where “ “ = ___;

Question 22

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

Answer 22

because it can update every single row of that category if where is not included.

Question 23

What is a foreign key?

Answer 23

Column’s value is one database is the SAME as another database’s so that you can associate it together

Question 24

How do you join two SQL tables?

Answer 24

using select, from, join “ “ using (“ “)

Question 25

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

Answer 25

as “ “

Question 26

What are some examples of aggregate functions?

Answer 26

max(), count(), avg(), sum()

Question 27

What is the purpose of a group by clause?

Answer 27

when you want to separate rows into groups and perform aggregate functions on those groups of rows
organizes your result sets into buckets
aggregate function is applied to the groupby