PostgreSQL

Question 1

What is PostgreSQL?

Answer 1

its an open source relational database.

Question 2

What is one way to see if PostgreSQL is running?

Answer 2

sudo service postgresql status

Question 3

what is a database schema?

Answer 3

Collection of tables and how they are structured

Question 4

What is a table?

Answer 4

• List of rows with the same attributes or columns

Question 5

• What is a row?

Answer 5

• List of values that add up with the attributes in the table

Question 6

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

Answer 6

• Structured Query Language is the primary way of interacting with relational databases. It’s a declarative language

Question 7

How do you retrieve specific columns from a database table?

Answer 7

• Select “column” from “table”

Question 8

• How do you filter rows based on some specific criteria?

Answer 8

• Where clause with pretiquite (where “firstName” = ‘Rob’)

Question 9

• What are the benefits of formatting your SQL?

Answer 9

• Makes it easier to read

Question 10

• What are four comparison operators that can be used in awhereclause?

Answer 10

• =, < , >, !=

Question 11

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

Answer 11

• Limit

Question 12

• How do you retrieve all columns from a database table?

Answer 12

• Select *

Question 13

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

Answer 13

• Order by column name (desc)

Question 14

• How do you add a row to a SQL table?* What is a tuple?

Answer 14

• Insert into “table” (“column”, “column”, “column”)

values (‘name’, ‘name’, name’)

Question 15

What is a tuple?

Answer 15

• A list of values in parenthesis

Question 16

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

Answer 16

• Add more than one tuple of values separated by commas.
  values (‘Ostrich Pillow’, ‘Feel comfy and cozy!’, 99, ‘self care’),
  (‘Tater Mitts’, ‘Scrub some taters!’, 6, ‘cooking’)

Question 17

• How do you get back the row being inserted into a table without a separateselectstatement?

Answer 17

• Returning *;

Question 18

• How do you update rows in a database table?

Answer 18

• Update “table” set “column” = ‘value’ where (pretiquite)

Question 19

• Why is it important to include awhereclause in yourupdatestatements?

Answer 19

• it will update every row

Question 20

*

* How do you delete rows from a database table?

Answer 20

• Delete statement

Question 21

• How do you accidentally delete all rows from a table?

Answer 21

• Not including a where clause

Question 22

When do you not put single quotes around values?

Answer 22

numbers and booleans do not need quotes

Question 23

What is a foreign key?

Answer 23

Column you can use to link to another table

Question 24

How do you join two SQL tables?

Answer 24

join “films” using (“filmId”)

Question 25

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

Answer 25

– as - - keyword

Question 26

What are some examples of aggregate functions?

Answer 26

avg(“column”) or count(*)

Question 27

What is the purpose of a group by clause

Answer 27

your aggregate is applied to those groups.