PostgreSQL

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 (RDBMS).

Other popular relational databases include MySQL (also free), SQL Server by Microsoft, and Oracle by Oracle Corporation.

Question 2

What are some advantages of learning a relational database?

Answer 2

Relational databases are arguably the most widely used kind of database. Many times when developers create a full stack developer, they are using a relational database.

Question 3

What is one way to see if PostgreSQL is running?

Answer 3

sudo service postgresql status

Question 4

What is a database schema?

Answer 4

A collection of tables is called a schema. A schema defines how the data in a relational database should be organized.

Question 5

What is a table?

Answer 5

A table is data that is in a list of rows where rows each have the same set of attributes.

Question 6

What is a row

Answer 6

A single instance of record in that table

Question 7

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

Answer 7

SQL is a declarative programming language. In declarative languages, programmers 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

Use the select keyword followed by the name of the column.

Question 9

How do you filter rows based on some specific criteria?

Answer 9

Use the select and where clause; expression that evaulates to true or false

Question 10

What are the benefits of formatting your SQL?

Answer 10

For 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

Keyword limit followed by a number for the number of rows

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

Keyword order by column name ___ (default is ascending) and if want descending put desc

Question 15

How do you add a row to a SQL table?

Answer 15

insert into “name of table to insert to” (“column names separated by commas”)
values (’text values wrapped in single quotes’, number values with literal numbers);

Question 16

What is a tuple?

Answer 16

In SQL, a list of values is referred to as a tuple.

Question 17

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

Answer 17

Data rows can be batch inserted into a database table by specifying more than one tuple of values, separated by commas

Question 18

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

Answer 18

Keyword returning *;

Question 19

How do you update rows in a database table?

Answer 19

update “table name”

set “attribute column name” = ‘value’ and no single quotes if it’s a number value

Question 20

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

Answer 20

You don’t want to update every row to have the same value (unless that is what you intend to do)

Question 21

How do you delete rows from a database table?

Answer 21

Keyword delete from and table name and followed a where clause!!!! If not, the entire table will be deleted

Question 22

How do you accidentally delete all rows from a table?

Answer 22

By not specifying where

Question 23

What is a foreign key?

Answer 23

Is a set of attributes in a table that refers to the primary key of another table. The foreign key links these two tables.

Question 24

How do you join two SQL tables?

Answer 24

Use the join keyword followed by “tableName” followed by using keyword followed by (“foreign key”);

Question 25

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

Answer 25

Use as (e.g table_name as alias_name)