postgres

Question 1

What is PostgreSQL and what are some alternative relational databases?

Answer 1

PostgreSQL is a relational database management system, other relational databases are MySQL, SQL Server, Oracle

Question 2

What are some advantages of learning a relational database?

Answer 2

good fit for storing related data, support good guarantees about data integrity, arguably one of the most widely used kind of database

Question 3

What is one way to see if PostgreSQL is running?

Answer 3

top command

Question 4

What is a database schema?

Answer 4

a collection of tables

Question 5

What is a table?

Answer 5

data stored in relations, a list of rows with information

Question 6

What is a row?

Answer 6

a line in a table containing related information

Question 7

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

Answer 7

primary way of interacting with relational databases, unlike JavaScript it is declarative not imperative where we describe what we 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 “specificColumn”

from “databaseTable”

Question 9

How do you filter rows based on some specific criteria?

Answer 9

select “specificColumn”
from “databaseTable”
where “x” = “y”

Question 10

What are the benefits of formatting your SQL?

Answer 10

readability

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

select “specificColumn”
from “databaseTable”
limit x

Question 13

How do you retrieve all columns from a database table?

Answer 13

select *

from “databaseTable”

Question 14

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

Answer 14

select *
order by “x” desc (asc is default)
from “databaseTable”

Question 15

How do you add a row to a SQL table?

Answer 15

insert into “SQLTableName” (“property”

values (“propertyValue”)

Question 16

What is a tuple?

Answer 16

in SQL a tuple is a list of values

Question 17

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

Answer 17

insert into “SQLTableName” (“property”
values (“propertyValue1”),
(“propertyValue2”),
(“propertyValue3”)

Question 18

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

Answer 18

returning *;
or
returning “rowname”;

Question 19

How do you update rows in a database table?

Answer 19

update “SQLTableName”

set “propertyName” = ‘newValue’

Question 20

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

Answer 20

If there is no where clause, then every row will be updated

Question 21

How do you delete rows from a database table?

Answer 21

delete from “SQLTableName”

where “propertyName” = ‘value’

Question 22

How do you accidentally delete all rows from a table?

Answer 22

exclude the where clause

Question 23

What is a foreign key?

Answer 23

a column referring to the same values in different tables

Question 24

How do you join two SQL tables?

Answer 24

select *
from “x”
join “y” using (“xy”)

Question 25

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

Answer 25

“x” as “y”

Question 26

What are some examples of aggregate functions?

Answer 26

sum, count, min, max,

Question 27

What is the purpose of a group by clause?

Answer 27

perform aggregate functions on groups of rows