PostgreSQL

Question 1

What is PostgreSQl and what are some alternative relational databases?

Answer 1

Open source object-relational database system

alternatives: mySQL, SQL server, Oracle

Question 2

What are some advantages of learning a relational database?

Answer 2

You work with the SQL language, and a majority of databases use SQL

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

collection of tables in sql

Question 5

What is a table?

Answer 5

list of rows each having the same set of attributes.

ex. student table can all have attributes: “firstName” , “lastName” , and “dateOfBirth

Question 6

What is a row?

Answer 6

a record of the table with data

Question 7

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

Answer 7

Structured Query Language - it is declarative meaning programmers describe the results they want and the programming environments gets those results

Question 8

How do you retrieve specific columns from a database table?

Answer 8

Select “columnName” from “tableName”;

Question 9

How do you filter rows based on some specific criteria?

Answer 9

Where “” = ‘’

Question 10

What are the benefits of formatting your SQL?

Answer 10

easier to read

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

*

Question 14

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

Answer 14

order by

Question 15

How do you add a row to a SQL table?

Answer 15

Insert into “tableName” (“columnName”) values (‘valueName’) returning *;

Question 16

What is a “tuple”?

Answer 16

A tuple is simply a row contained in a table in the tablespace.

Question 17

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

Answer 17

Insert into “tableName” (“columnNames”, etc etc.) values (‘value’, etc etc) returning *;

Question 18

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

Answer 18

returning *

Question 19

How do you update rows in a database table?

Answer 19

returning *

Question 20

How do you update rows in a database table?

Answer 20

Update “table” set “columnName” = ‘value’ where “columnName = ‘newValue’;

Question 21

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

Answer 21

So you dont update everything inside of the table

Question 22

How do you delete rows from a database table?

Answer 22

Delete from “tableName” where “columnName” = value returning *;

Question 23

How do you accidentally delete all rows from a table?

Answer 23

Delete from “tableName” DONT DO THIS!!

Question 24

What is a foreign key?

Answer 24

Value in column used to link two tables

Question 25

How do you join two SQL tables?

Answer 25

join

Question 26

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

Answer 26

Aliasing use as

Question 27

What are some examples of aggregate functions?

Answer 27

min(), sum(), and every()

Question 28

What is the purpose of a group by clause?

Answer 28

Instead, you want to separate rows into groups and perform aggregate functions on those groups of rows. This is done with a group by clause.