This 2nd VoiceThread is to makeup for the missed

Feb. 2nd class

Topic: Database Design

By: George Saban

Intro to Database• Binary Digits = bits• US statistician John Tukey invents the term "bit" (binary digit, 0 or 1) for the

smallest element of information to describe a two-state system.

What is a Database?

From bits to Database

The Cabinet Analogy

Pros and Cons of DBMS• Advantages of database processing

• Getting more information from the same amount of data.• Sharing data.• Balancing conflicting requirements.• Controlling redundancy.• Facilitating consistency.• Improving integrity.• Expanding security.• Increasing productivity.• Providing data independence.

• Disadvantages of database processing • Larger file size.• Increased complexity.• Greater impact of failure.• More difficult recovery.

Types of Databases

• 1. Hierarchical• 2. Network• 3. Relational *• 4. OO DB• 5. Hybrid

Relational Database (RDBMS)

• A collection of interrelated tables.

• Types of Relationships: (next slides)

Types of Relationships

• One-to-one relationship

Types of Relationships

• One-to-many relationship

Types of Relationships• Many-to-many relationship

So What?

• Smallest unit of data• Relationship between a record and an object

The Request/Response Cycle

The Big Picture: Business Process Model

Types of Keys• Primary key – is an attribute or set of attributes that will uniquely identify records

in a table. Example: social-security number, driver license, employee-ID, unique sequence number, etc.

• Secondary key – a non-key field that could potentially be used as the primary key. Example: product-ID, UPC-code, etc. This is similar to an alternate key.

• Alternate key – a non-key field that could potentially be used as the primary key. Example: product-ID, UPC-code, etc. This is similar to a secondary key.

• Candidate key – the same as secondary key and alternate key.• Foreign key – it is a non-key field in a table but is actually a primary key of another

table. It exists as a link (to maintain relation) between the two tables.• Non-primary key or non-prime attribute – is an attribute or attributes that is

neither a primary key nor a candidate key. Example: first name, address, etc.• Combination key – is a primary key made up of multiple keys. Example: StudentID

+ lastname + firstname.

The Normalization Process• Step I: Write down all the fields needed to support your application.• Step II: Think if these fields repeat or not. And eliminate fields that can be calculated.• Step III: Yank out fields that repeat and store it in a separate table and leave those fields that

does not repeat into this existing table. Group similar fields into a table.• Step IV: Select the primary key field(s) for each table. And underline the primary key field

(PK).• Step V: Normalize the table by putting the database in first normal form (or 1NF). Meaning,

tables should have no repeating fields.• Step VI: Continue normalization process by putting the database in second normalized form

(or 2NF). Meaning, all non-key fields on a table should be dependent on the entire primary key fields and not just part of it. The table should be already in 1NF and the primary key field should be a combination key field.

• Step VII: Continue normalization process by putting the database in its third normalized form (or 3NF). Meaning, all non-key fields should not be dependent on another non-key field. The table should be already in 2NF.

• Step VIII: Assign names to these tables. • Step IX: Draw table relationships, also called entity relationship diagram (ERD).

Entity Relationship Diagram (ERD)

• Note the interrelationships of tables: a database.• When asked to

draw/design a DB—draw an ERD.

Thank You!

• Thank you for your patience and for being flexible in making up the missed classes.• Comment in as many slides to earn full credit for Week #6.• Please make sure you digested all the artifacts posted in Canvas under

Week #6.• Complete also the deliverable for the week.• I hope to see you on Week #7 to have a conversation regarding

development strategies.