postgres

Question 1

What is PostgreSQL and what are some alternative relational databases?

Answer 1

open source relational database management system. MySQL, SQL server by Microsoft, and Oracle.

Question 2

What are some advantages of learning a relational database?

Answer 2

Full stack web development always involves databases.

Question 3

What is one way to see if PostgreSQL is running?

Answer 3

running top command on terminal. sudo service postgresql status command

Question 4

What is a database schema?

Answer 4

a collection of tables. dictates the structure of your data in your database

Question 5

What is a table?

Answer 5

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

Question 6

What is a row?

Answer 6

single data record within a table for a specific item.

Question 7

what is pgweb

Answer 7

graphical user interface of postgres server.

Question 8

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

Answer 8

SQL is a declarative language and JavaScript is an imperative language.

Question 9

How do you retrieve specific columns from a database table?

Answer 9

select “name”

Question 10

How do you filter rows based on some specific criteria?

Answer 10

using the where clause and condition (predicate)

Question 11

What are the benefits of formatting your SQL?

Answer 11

better readability. Your SQL can get very complex.

Question 12

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

Answer 12

= < > !=

Question 13

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

Answer 13

limit clause

Question 14

How do you retrieve all columns from a database table?

Answer 14

select *

Question 15

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

Answer 15

desc

Question 16

How do you add a row to a SQL table?

Answer 16

insert into statement

Question 17

What is a tuple?

Answer 17

a list of values

Question 18

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

Answer 18

you can specify more than one tuple, separated by commas.

Question 19

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

Answer 19

returning clause

Question 20

How do you update rows in a database table?

Answer 20

update statement

Question 21

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

Answer 21

because that will modify the every row in the table

Question 22

How do you delete rows from a database table?

Answer 22

delete from clause

Question 23

How do you accidentally delete all rows from a table?

Answer 23

without using where clause

Question 24

why does update or delete statements not work?

Answer 24

foreign key constraint

Question 25

What is a foreign key?

Answer 25

columns that have the same name as columns in other tables. its used to join tables together.

Question 26

How do you join two SQL tables?

Answer 26

using join clause

Question 27

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

Answer 27

“tableName”.”columnName” as “tempName” (aliasing)

Question 28

What are some examples of aggregate functions?

Answer 28

count, sum, avg

Question 29

What is the purpose of a group by clause?

Answer 29

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