Data Science and Analytics - Stephan SorgerFor GoDaddy, launch hosting account to see cPanel (shown). Click on MySQL Database Wizard . MySQL Server: Setup ... from tables using comma

© Stephan Sorger 2016; www.StephanSorger.com; Data Science: SQL: MySQL 1

Disclaimer:

• All images such as logos, photos, etc. used in this presentation are the property of their respective copyright owners and are used

here for educational purposes only

• Some material adapted from: Sorger, Stephan. “Marketing Analytics: Strategic Models and Metrics. Admiral Press. 2013.

Introduction to

Data Science and Analytics

Stephan Sorger www.StephanSorger.com

Unit 6B. SQL: Overview and Coding SQL Coding Session in MySQL

http://www.stephansorger.com/


Outline/ Learning Objectives


Category Description

Hosting Obtaining hosting server for MySQL (free or paid)

Setup Setting up the MySQL Server on hosting platforms

Import Importing databases into MySQL Server

Structure Data structure; Showing tables within databases

SHOW, SELECT Commands to display data and choose data

Sorting, Filtering Commands to sort and filter data

Creating Creating, Dropping, and Altering databases and tables


MySQL: Hosting


Go to

000webhost.com

(or other similar

Web hosting service)

and get an account


MySQL Server: Setup


Creating MySQL

Databases for

hosting accounts

on GoDaddy.com



MySQL Server: Setup

For GoDaddy,

launch hosting

account to see

cPanel (shown).

Click on MySQL

Database Wizard


MySQL Server: Setup


Enter name for

database


MySQL Server: Setup


Enter username

and password


MySQL Server: Setup


Select

privileges

for user


MySQL Server: Setup


Select

phpMyAdmin


MySQL: Importing Databases


Select your Database

(Database1)




Select Import




MySQL Sample Databases:

dev.mysql.com/doc/index-other.html

For our example: world database




Choose File:

Dataset:

world.sql

Click “Go”

(bottom of page)




Imported OK;

Click “Database1”


MySQL: Data Structure


Check “City” Table

within World database

Click on SQL tab




In SQL tab, enter

“SHOW DATABASES”

and hit “Go”

SQL commands

also called “queries”

are in ALL CAPS

Table entries are in lower case or Mixed Case




Shows databases:

information_schema

(already in SQL server)

Database1

(we created)




In SQL tab, enter

“SHOW TABLES”

and hit “Go”




Tables:

City

Country

Country Language


MySQL: SHOW Command


View columns of table

Click on SQL tab

Syntax:

SHOW COLUMNS FROM (table)

Here:

SHOW COLUMNS FROM City

Then click Go


MySQL: SHOW Command


Results:

See columns from table

Note PRI (primary) key

Here, PRI = ID field


MySQL: SHOW Command


Click on file structure list

in left column to see table

Here, click on “City”


MySQL: SELECT Command


SELECT Name FROM City

and click Go

Note column names on right

Note commands on bottom




Result:

Names of cities




Select multiple columns

from tables using comma (,)

between column labels

Note semicolon at end of line

(most compilers will run command without semicolon if command is only 1 line)

SELECT Name, CountryCode FROM City;




Result:

Names of cities

AND

Names of Country Codes




Insert wildcard

character (*) to

retrieve all information

SELECT * FROM City




Result:

Entire dataset


MySQL: SELECT with DISTINCT and LIMIT


DISTINCT:

To show only one

instance of a particular

value

SELECT DISTINCT CountryCode FROM City




Result:

Distinct country codes




Show only first 5

using LIMIT command

SELECT Name, CountryCode FROM City LIMIT 5




Result: First 5 entries




Select only limited set of entries

From start point (say, 5)

To a certain number of data points (say, 10)

(Computers start counting at 0, not at 1,

so results will show “6”, not “5”

SELECT Name, CountryCode FROM City LIMIT 5, 10




Result: Results 5 - 15




Fully Qualified Names:

“dataset.label”

Handy if working on

multiple databases

with the same column

SELECT City.Name FROM City




Results: Same as before

Note names in order as

found in the original table;

Can be confusing.

Alternative: Sort.


MySQL: Sorting


Sort results using

ORDER BY command

SELECT Name FROM City ORDER BY Name


MySQL: Sorting


Results are now in

alphabetic order


MySQL: Sorting


Sorting multiple columns,

specifying order parameter

SELECT Name, CountryCode, District FROM City ORDER BY Name


MySQL: Sorting


Results:

Multiple columns,

sorted by Name


MySQL: Sorting


Sequential Sort:

Sort by x, then by y

SELECT Name,CountryCode,District from City ORDER BY name,CountryCode


MySQL: Sorting


Result:

Sort by Name,

then by Country Code

(not very interesting

in this case, because

data is unique for each area)


MySQL: Sorting


Sorting in reverse

direction; from high to low

DESC = Descending

ASC = Ascending

SELECT Name, CountryCode FROM City ORDER BY Name DESC


MySQL: Sorting


Result: Names from Z – A

BUT: Algorithm lists

special characters,

such as umlauted vowels,

AFTER Z


MySQL: Sorting


Select highest value

(or lowest value)

SELECT Name, Population FROM City ORDER BY Population LIMIT 1


MySQL: Sorting


Results:

Adamstown has the

smallest population,

with only 42 people


MySQL: Sorting


Select highest value

(or lowest value)

SELECT Name, Population FROM City ORDER BY Population DESC LIMIT 1


MySQL: Sorting


Results:

Mumbai has the

largest population,

with 10,500,000 people


MySQL: Filtering


Filtering:

Want only areas

within country code ‘AFG’

SELECT Name, CountryCode FROM City WHERE CountryCode=‘AFG’


MySQL: Filtering


Results


MySQL: Filtering


Filtering:

Want to list

“small cities”,

i.e. areas

with population

under 10,000

SELECT Name, Population FROM City WHERE Population <= 10000

(could also show “large cities”) :

SELECT Name, Population FROM City WHERE Population >= 10000


MySQL: Filtering


Result:

Listing of “small” cities

in ID order

(could also sort if

desired)


MySQL: Filtering


Filtering:

Want to list

“medium cities”

i.e. areas

with population

between

10,000 and 50,000:

SELECT Name, Population FROM City WHERE Population BETWEEN 10000 AND 50000

OR

SELECT Name, Population FROM City WHERE Population >= 10000 && Population <= 50000


MySQL: Filtering


Result:

“Sweet spot” cities

between 10,000 and

50,000


MySQL: Logical Operators


Find name of city

within AFG with a

population greater

than 200,000

SELECT Name, CountryCode FROM City WHERE CountryCode=‘AFG’ AND Population>200000




Result: Two cities

met both criteria




Find name of city

within NLD

OR with a population

greater than 400,000

SELECT Name, CountryCode, Population

FROM City WHERE CountryCode=‘NLD’ AND Population>400000




Result: Three cities

met at least one of the

criteria


MySQL: Searching


Use REGEXP

(regular expression)

to search for item.

Here, we want to

search for any district

with the word “Holland”

in it.

SELECT Name, District FROM City WHERE District REGEXP 'Holland'


MySQL: Searching


Results:

Many districts have

the word “Holland”

in them


MySQL: Special Columns


Create special columns

using math: +, -, *, /

For example, what if

population were to grow by 10%?

SELECT Name, Population, Population*1.1 AS Population_Growth FROM City


MySQL: Special Columns


Result:

Special Column temporarily

inserted in database:

Population Growth

Shows population + 10%

SELECT Name, Population, Population*1.1 AS Population_Growth FROM City


MySQL: CREATE Database


Create new database

called “database2”

CREATE DATABASE database2

To delete database:

DROP DATABASE database2


MySQL: CREATE Table


Create new table

through phpMyAdmin

By clicking on Database


MySQL: CREATE Table


Within phpMyAdmin:

Create table:

Enter Name

Enter number of columns


MySQL: CREATE Table


Within MySQL:

Create new table: CREATE

Drop or rename table:

DROP TABLE signup

RENAME TABLE signup TO users

Create new table

for website

where people can

sign up for emails


MySQL: CREATE Table


CREATE TABLE signup ( Open bracket; Create new lines

id int NOT NULL AUTO_INCREMENT First variable: id; data type: Integer; Automatically add 1

name varchar (30) NOT NULL Second variable: name; alphanumeric text; Required

email varchar (30) NOT NULL Third variable: email; max length: 30 char. ; Required

PRIMARY KEY (id) Declare primary key; in this case, “id”

) Close bracket


MySQL: CREATE Table


Click on Structure

to see table structure

id underlined

PRIMARY KEY


MySQL: CREATE Table


Manually enter data

by clicking Insert tab,

then click Go


MySQL: Alter Table


Results:

-Data inserted

-ID incremented

To Delete a Row:

DELETE FROM signup WHERE name = ‘Kathy Kar’


MySQL: Alter Table


Add column:

phone (phone number)

To add a column:

ALTER TABLE signup ADD phone varchar(10) NOT NULL

To delete a column:

ALTER TABLE signup DROP COLUMN phone


MySQL: Alter Table


Results:

New column inserted:

“phone”


MySQL: Reference Manuals


dev.mysql.com/doc/index.html


MySQL:



MySQL:



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Documents

Data Science and Analytics - Stephan SorgerFor GoDaddy, launch hosting account to see cPanel (shown). Click on MySQL Database Wizard . MySQL Server: Setup ... from tables using comma