PostgresSQL

Question 1

What is PostgreSQL and what are some alternative relational databases?

Answer 1

relational database system/digital database based on the relational model of data/object-relational database management system
MySQL, SQL Server by Microsoft, and Oracle by Oracle Corporation.

Question 2

What are some advantages of learning a relational database?

Answer 2

easy to store related data
they support good guarantees about data integrity. They can store and modify data in a way that makes data corruption as unlikely as possible.
categorizing, ease of use, accuracy, commonly used
multiple users can access

Question 3

What is one way to see if PostgreSQL is running?

Answer 3

top command
pgweb and the local server port
sudo service postgresql status

Question 4

What is a database schema?

Answer 4

design that represents the storage of your data in a database.
A schema defines how the data in a relational database should be organized in tables

Question 5

What is a table?

Answer 5

A table is a list of rows each having the same set of attributes. where relational data is stored

Question 6

What is a row?

Answer 6

a record in that spreadsheet with the same set of attributes

Question 7

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

Answer 7

the language to interact with databases

it is a declarative language like HTML and CSS so the programmer has to describe their desired result

Question 8

How do you retrieve specific columns from a database table?

Answer 8

select statement
select “name”,
double quotes

Question 9

How do you filter rows based on some specific criteria?

Answer 9

where clause

where “category” = ‘cleaning’;

Question 10

What are the benefits of formatting your SQL?

Answer 10

makes it more readable and easy to use

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
limit 1;
integer maximum

Question 13

How do you retrieve all columns from a database table?

Answer 13

select * ‘star’

Question 14

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

Answer 14

order by clause then optional desc

default asc`

Question 15

How do you add a row to a SQL table?

Answer 15

insert statement is a means of adding rows to a table
insert into “products” (“name”, “description”, “price”, “category”)
values (‘Ostrich Pillow’, ‘Feel comfy and cozy!’, 99, ‘self care’);

Question 16

What is a tuple?

Answer 16

a list of values

that is being inserted into a db

Question 17

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

Answer 17

by specifying more than one tuple of values, separated by commas.

Question 18

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

Answer 18

returning clause

Question 19

How do you update rows in a database table?

Answer 19

update statement
set clause
where clause

Question 20

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

Answer 20

where clause in your update statements to only target specific

Question 21

How do you delete rows from a database table?

Answer 21

using the delete from statement

Question 22

How do you accidentally delete all rows from a table?

Answer 22

by not specifying where to delete from

Question 23

What is a foreign key?

Answer 23

a column that links between 2 tables

same value

Question 24

How do you join two SQL tables?

Answer 24

join statement An SQL join clause is a way of combining data from two different database tables into one result set.

Question 25

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

Answer 25

the as keyword

Question 26

What are some examples of aggregate functions?

Answer 26

count, average, max, min(), sum(), and every()

Question 27

What is the purpose of a group by clause?

Answer 27

to separate rows into groups and perform aggregate functions on those groups of rows