DB Intro

Intro to the Data Tier

Information Technology

So far we've learned how to

• Present Data

• Modify data in our local code

• Transfer data between pages

  • Directly

  • Indirectly

Let's Review.........

Multiple Choice

What type of data is quickly available to users but very difficult to update?

• Session Variable

• Local Variable

• Parameter

• Static Content on HTML Page

Multiple Choice

What type of data is immediately available to code anywhere on the same page and is very easy to update?

• Session Variable

• Local Variable

• Parameter

• Static Content on HTML Page

Multiple Choice

What is the best method to transfer data directly from one page to another?

• Session Variable

• Local Variable

• Parameter

• Static Content on HTML Page

Multiple Choice

What type of data is stored in a way that makes it available to any page the user views?

• Session Variable

• Local Variable

• Parameter

• Static Content on HTML Page

Multiple Choice

Other than HTML, do ANY of the previous options store data for later use?

• Yes

• No

Multiple Choice

Other than HTML, are any of the previous options saved if you turn the computer off?

• Yes

• No

Multiple Choice

Other than HTML, can ANY of the previous options handle very large amounts of data?

• Yes

• No

So we're missing a piece right?

• Holds data for short term or long term use

• Usually uses

  • Databases*

  • File Systems

• Usually can handle very large amounts of data

• Peformance starts becomeing an issue

​

​Data Tier

• Information is stored in specialized software such as Oracle, MySQL, SQL Server, etc.

• Much faster at searching and sorting but is expensive and complex

​Database

• Store data in files on local or network storage.

• Examples include google docs, text files, or program created files

• Usually cheap and easy to use but much slower when searching or sorting

​File System

Storage Options

Multiple Choice

Which would be best for data that is not accessed very often and only by a limited amount of people?

• File System

• Database

Multiple Choice

Which would be best for data that is accessed very frequently by a large number of people?

• File System

• Database

Multiple Choice

Which would be best for data that is commonly needs to be presented a certain way or you are searching for very specific data?

• File System

• Database

Multiple Choice

Which would be best for data that people usually try and find very broad data and can browse through whatever is presented?

• File System

• Database

Database Server Software

• Stores data in a structured, relational, and efficient manner

• Allows for east searching and the ability to arrange the data in the way you need it

• Provides features important to business continuity

  • Security: Controls access to the data

  • Scalability: Making sure the system has enough capacity to handle the planned load

  • Redundancy : Guards against hardware or system failure to ensure data is not lost and/or is still available to applications

Multiple Choice

Which function failed if a hacker gains access to user names and passwords?

• Security

• Scalibility

• Redundancy

Multiple Choice

Which function failed if the system gets too busy and users have to wait too long?

• Security

• Scalibility

• Redundancy

Multiple Choice

Which function failed if no users are able to use any part of the system because that database server was lost in a fire?

• Security

• Scalibility

• Redundancy

Can be VERY expensive but have mission critical abilities

Examples:

• Oracle

• Microsoft SQL Server

​Commercial

Free but usually have limited functionality

Examples:

• MySQL

• Postgre

Open Source

Types of database Software

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​There are also applications like Microsoft Access that are "light" databases that do not need to run on a server

Poll

Which makes more sense, one textbook for each class or one big book for all your classes?

• One for each class

• One big book with everything

​Relational Databases

• Are organized in a way that groups information in a way that makes it easier to either focus in on very specific information or combine a lot of information

• Data is stored in tables that contain information usually limited to one category

• These tables are linked by something they have in common

Subject | Subject

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• Employee Number

• First Name

• Last Name

• Hire Date

• Certification Area

​Teachers

• Title

• Subject

• Period

• Teacher

Classes

Table Examples

How are they related?

​Tables include "Fields" which is where the specific information is stored

• Employee Number

• First Name

• Last Name

• Hire Date

• Certification Area

​Teachers

• Title

• Subject

• Period

• Teacher

Classes

"Joining" Tables

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Structured Query Language (SQL)

​Pronounced like "sequel"

• Language for building queries that are used for accessing or modifying data stored in a database

• Only has four basic commands:

  • Select

  • Insert

  • Update

  • Delete

• BUT has many functions and modifiers that can make things very complex!

Let's Review

Multiple Choice

What language is used for accessing information in a database?

• Assembly

• Java

• SQL

• HTML

Multiple Choice

What is the proper name for requesting information from a database?

• join

• link

• index

• query

Multiple Choice

What is the proper name for getting information from different tables using a common field?

• join

• link

• index

• query

Multiple Choice

Something named "Classrooms" is most likely a database:

• Table

• Field

Multiple Choice

Which database server software would most likely be used for a credit card company?

• Text Files

• Oracle

• MySQL

• Microsoft Access

Multiple Choice

Something named "RoomNumber" is most likely a database:

• Table

• Field

Multiple Choice

Which field would most likely be the link between these tables:

Players: A list of players on a football team

GameEvents: A list of events by a particular player in a game

• Event Type (tackle, interception, touchdown, etc)

• Event Time

• Player Jersey Number

What's Next

CodeHS: Hour of SQL Module

Due Friday for EVERYBODY

Subject | Subject

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