SQL

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

Linter, NexusDB, Paradox

Question 2

What are some advantages of learning a relational database?

Answer 2

Easy Access to Data, Simple Model, Data Accuracy, Flexibility

Question 3

What is one way to see if PostgreSQL is running?

Answer 3

using the top command

Question 4

What is a database schema?

Answer 4

A collection of tables

A schema defines how the data in a relational database should be organized

Question 5

What is a table?

Answer 5

Relational databases store data in relations, commonly referred to as tables

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

Question 6

What is a row?

Answer 6

a record of data

Question 7

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

Answer 7

SQL is a declarative programming language

you tell the JavaScript what to do and how to do it. in SQL describe the results they want and the programming environment comes up with its own plan for getting those results

Question 8

How do you retrieve specific columns from a database table?

Answer 8

select and from

Question 9

How do you filter rows based on some specific criteria?

Answer 9

where

Question 10

What are the benefits of formatting your SQL?

Answer 10

consistent style and readability.

Question 11

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

Answer 11

, =, and !=

Question 12

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

Answer 12

limit

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” ()

value ()

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

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 *

Question 19

How do you delete rows from a database table?

Answer 19

delete from “table name”

Question 20

How do you accidentally delete all rows from a table?

Answer 20

if you just target the tables name

Question 21

How do you update rows in a database table?

Answer 21

update “table name”

set “row name” = value

Question 22

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

Answer 22

it would update every row in the table

Question 23

What is a foreign key?

Answer 23

a column or set of columns that allow us to establish a referential link between the data in two tables

Question 24

How do you join two SQL tables?

Answer 24

join “table name” using (“Id”);

Question 25

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

Answer 25

as keyword

“tablename”.”rowname” as new name

Question 26

What are some examples of aggregate functions?

Answer 26

min(), sum(), every(), max(), bool_or(), bool_and()

Question 27

What is the purpose of a group by clause?

Answer 27

when you dont want to ask a question to every row