Postgres

Question 1

What is PostgreSQL and what are some alternative relational databases?

Answer 1

a powerful, free, open source Relational Database Management System (RDBMS) MySQL, SQL Server, Oracle

Question 2

What are some advantages of learning a relational database?

Answer 2

they support good guarantees about data integrity, store and modify data in a way that makes data corruption as unlikely as possible

Question 3

What is one way to see if PostgreSQL is running?

Answer 3

sudo service postgresql status, or top

Question 4

What is a database schema?

Answer 4

collection of tables

Defines how the data in a relational database should be organized

Question 5

What is a table?

Answer 5

relations - where relational databases are store data in a set of rows

Question 6

What is a row?

Answer 6

Having the same set of attributes

Question 7

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

Answer 7

Structured Query Language (SQL) - primary way of interacting with relational databases - a declarative programming language

Question 8

How do you retrieve specific columns from a database table?

Answer 8

Querying a database typically takes the form of a select statement.
select “name”,
“price”
from “products”;

Question 9

How do you filter rows based on some specific criteria?

Answer 9

where “category” = ‘cleaning’;

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

=, < >, !=

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

Select *

Question 14

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

Answer 14

order by “columnName” asc/desc

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.

Question 16

What is a tuple?

Answer 16

list of values

Question 17

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

Answer 17

batch inserted into a database table 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 followed by set clause

Question 20

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

Answer 20

Only need to update a specific item in the table

If no where clause it would update every row in the table

Question 21

How do you delete rows from a database table?

Answer 21

Using a delete statement followed by table name

Question 22

How do you accidentally delete all rows from a table?

Answer 22

Delete from “tableName” with nothing else

Need to specify with a where clause

Question 23

What is a foreign key?

Answer 23

the one specific column that links one table to another table.

Question 24

How do you join two SQL tables?

Answer 24

Using the join clause

Question 25

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

Answer 25

Using alias column names

Question 26

What are some examples of aggregate functions?

Answer 26

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

Question 27

What is the purpose of a group by clause?

Answer 27

separate/cluster rows into groups and perform aggregate functions on those groups of rows