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). Some other relational databases are MySQL or Oracle.

Question 2

What are some advantages of learning a relational database?

Answer 2

It works well with storing related data, and almost all of them use the same language so it isn’t hard to switch from one relational database to another.

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 that correspond to each other

Question 5

What is a table?

Answer 5

a collection of data that is related with each other

Question 6

What is a row?

Answer 6

collection of values that correspond to the attributes of that table

Question 7

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

Answer 7

SQL is a powerful way of retrieving, creating, and manipulating data in a relational database. It is a declarative language where as JavaScript is a imperative language

Question 8

How do you retrieve specific columns from a database table?

Answer 8

By including them in the select statement

Question 9

How do you filter rows based on some specific criteria?

Answer 9

using the where statement followed by the row name and then the criteria

Question 10

What are the benefits of formatting your SQL?

Answer 10

easier readability

Question 11

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

Answer 11

=, , !=

Question 12

How do you retrieve all columns from a database table?

Answer 12

by including an asterisk in the select statement

Question 13

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

Answer 13

using an order by statement

Question 14

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

Answer 14

using a limit statement

Question 15

How do you add a row to a SQL table?

Answer 15

by using insert into, the table name, then the column names you want to edit. Then on the following line use a values clause and add the value in order to the listed column names above

Question 16

What is a tuple?

Answer 16

a list of values

Question 17

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

Answer 17

list multiple tuples

Question 18

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

Answer 18

by using returning followed by an asterisk

Question 19

How do you update rows in a database table?

Answer 19

Using the update clause followed by the table name, then use the set clause and set a value or values to one or more column names. then display exactly which row you want to change by using the where clause.

Question 20

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

Answer 20

So it doesn’t effect the whole column of values

Question 21

How do you delete rows from a database table?

Answer 21

By using the delete from clause followed by the table name. using the where clause after will let you specify what item or items you want to delete.

Question 22

How do you accidentally delete all rows from a table?

Answer 22

when you only include the delete from line followed by a table name

Question 23

What is a foreign key?

Answer 23

A key or id that relates to another tables contents

Question 24

How do you join two SQL tables?

Answer 24

using the from and join clause

Question 25

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

Answer 25

use the as keyword

Question 26

What is the purpose of a group by clause?

Answer 26

to apply the aggregate functions to a clump of rows