Transcript Structured Database Running on Appaserver

Structured Database
Running on Appaserver
What is a structured database?
 What is Appaserver?

©Tim Riley
What is a structured
database?

Unstructured database:
Do this better than
Google, and you'll
become a billionaire.
©Tim Riley
An unstructured database is a set of documents
available to a software crawler. The crawler
traverses each document and makes a
searchable index. Database users are presented
with a text field to search for key words. Those
documents deemed significant are presented to
the user.
What is a structured
database?
Unstructured database:
 Structured database:

In a structured database, a specialist
categorizes all of the organization's
information into sets.
©Tim Riley
What is a structured database?
Set Name
Every set has a name. The name should be either
a noun or an event. All of the organization's
persons, places, and things should be categorized.
Also, all of the organization's events, starting with
its transactions, should be categorized.
©Tim Riley
What is a structured database?
Set Name
Database sets are also known as:
* categories
* tables
* folders
* collections
©Tim Riley
Represent database sets in rectangles,
with the set name above the title line.
What is a structured database?
Set Name
Attribute 1
Attribute 2
…
Attribute n
Describe set characteristics with attributes.
Attributes are used to divide a set into many
subsets.
©Tim Riley
datatype
datatype
datatype
Attributes are also
known as:
* columns
* fields
* properties
What is a structured database?
Set Name
Attribute 1
Attribute 2
…
Attribute n
datatype
datatype
datatype
Each attribute is assigned a datatype.
Examples of datatypes:
* Integer number
* Floating point (real) number
* Date
* Time
* Line of text
* Notepad of text
©Tim Riley
Example Set
Person
full_name
skin_color
religion
height_inches
weight_pounds
birth_date
annual_income
general_characterists
These attributes help
describe a person.
©Tim Riley
text
text
text
integer
integer
date
float
notepad
Set Elements
Sets contain elements
Set elements are also known as:
* Members
* Tuples
* Rows
* Objects
* Records
Person
There are 3
elements in the
person set.
Full Name
Linus Torvalds
Guido van Rossum
Bill Henry Gates III
©Tim Riley
Making Subsets
Person
You can divide all persons
into two subsets: those
named Bill Henry Gates III,
and those who are not.
You can divide all persons
into two subsets: those
making over a billion dollars a
year, and those who do not.
©Tim Riley
full_name
skin_color
religion
height_inches
weight_pounds
birth_date
annual_income
general_characterists
text
text
text
integer
integer
date
float
notepad
Set Relationships
Set 1
Set 2
Verb phrase
Sets are related to other sets.
Set relationships are identified
using verbs.
©Tim Riley
Set Relationships
Person
State
Reside in
Sets are related to other sets.
Set relationships are identified
using verbs.
©Tim Riley
Many Set Relationships
Person
State
Reside in
Attend
School
One set can be related to
more than one set.
©Tim Riley
Many Set Relationships
Person
State
Reside in
Born in
One set can be related to
another set twice, three
times, etc.
©Tim Riley
Set Relationship Types
Set 1
Set 2
Verb phrase
There are 5 types of set relationships:
* many-to-one
* one-to-many
* many-to-many
* one-to-one
* is-a
©Tim Riley
Many-to-one Relationship
Person
State
Reside in
many
”Many persons
one
reside in
one state.”
Therefore, there is a many-to-one relationship from person to
state with regard to residence.
©Tim Riley
One-to-many Relationship
Person
State
Has resident
many
one
Reverse the arrow to reverse the relationship. ”One state has as residents
many persons.”
Therefore, there is a one-to-many relationship from state to
person with regard to residence.
©Tim Riley
Many-to-many Relationship
Person
State
Visit
many
many
If you have a one-to-many relationship
going both ways, then you have a manyto-many relationship.
”One person can visit many states. And one state
can have as visitors many persons.”
Therefore, there is a many-to-many
relationship from person to state with
regard to visitation.
©Tim Riley
Many-to-many relationships can go both
ways. ”Therefore, there is a many-tomany relationship from state to person
with regard to visitation.”
One-to-one Relationship
Office
Phone
Has
one
one
One-to-one relationships are rare. More
often than not, you would move the
attributes of phone over to the office
category.
”One office has one phone.”
Therefore, there is a one-to-one
relationship from office to phone.
©Tim Riley
One-to-one relationships can go both
ways. ”One phone can be located in only
one office.”
Is-a Relationship
Accountant
Person
Is a
one
”An accountant is a person.”
Therefore, there is an is-a relationship from
accountant to person.
©Tim Riley
one
An is-a relationship is a special case
of a one-to-one relationship.
Is-a relationships enable inheritance
to take place. An accountant inherits
all the attributes of person plus has
additional attributes which help to
describe accountants.
Enforcing Business Rules
Two broad categories of business rule
enforcement are:
* Implementational restrictions (bad)
* Integrity constraints (good)
©Tim Riley
Enforcing Business Rules
Implementational restrictions are
business rules the information
system cannot enforce.
Person
State
Reside in
many
Although not common, a person could own a house in
several states. However, this particular database
design restricts the information system to recognize
only one of them.
©Tim Riley
one
Enforcing Business Rules
Integrity constraints are business rules
the information system succeeds at
enforcing. Two imperative integrity
constraints are:
* Relational integrity
* Element uniqueness
©Tim Riley
Enforcing Business Rules
Relational integrity is the constraint that an element in
each set must exist in order for a relationship to exist
between them.
Person
many
A person can exist without
residing in a state.
©Tim Riley
State
Reside in
one
A state can exist without any persons
residing in it.
But both the person and the state must exist for that person to reside in that
state. In practical terms, the one set must have an existing element first. For
example, the state of California must first exist before assigning any persons
to California. This prevents the assignment of a person to a state that does not
exist, like the state of Caliifornia.
Enforcing Business Rules
Element uniqueness is the constraint that an element
cannot exist more than once in a set.
Person
full_name
text *
Only one person named Bill
Henry Gates III can belong to
the person set.
The set of attributes
enforcing uniqueness is
called the primary key.
©Tim Riley
To show that an attribute has been
assigned to the set of attributes
enforcing uniqueness, append an
asterisk.
Element Uniqueness
Natural primary key: the set of attributes that naturally
enforce uniqueness.
Person
Names are likely to be
naturally duplicated.
If a set has more than one
attribute assigned to its
primary key, then it's called a
multi-attribute primary key.
©Tim Riley
full_name
street_address
Therefore, assign the street
address (a place) as an
additional attribute to the
primary key.
text *
text *
Element Uniqueness
Primary keys naturally occur.
To identify the natural primary key, always
consider the four dimensions. Uniqueness can
always be naturally identified with:
1) Longitude
2) Latitude
3) Elevation
4) Time
©Tim Riley
All of the organization's places
should be categorized.
All events need a date/time
stamp.
Element Uniqueness
Surrogate primary key: a made-up attribute used to
store a sequential number to force uniqueness.
Historically, the attributes assigned as the
primary key must be immutable – they could
not change. To accommodate this restriction,
a made-up attribute was created to store a
sequential number.
Consider auditing transactions with
customer numbers, sales-representative
numbers, store numbers, and transaction
codes. Sheesh!
©Tim Riley
Surrogate primary keys are bad for
many reasons, including:
1) They allow for natural key
duplication, violating element
uniqueness!
2) They require an additional level of
indirection from which to audit.
3) They may inadvertently disclose
the organization's volume.
Element Uniqueness
Mutable primary keys: The value of primary keys can
change when using Appaserver.
Person
full_name
street_address
text *
text *
Historically, the attributes assigned as the primary key must be
immutable – they could not change. However, Appaserver
overcomes this restriction. Therefore, you can change the person's
name if she gets married or change the street address if he moves.
©Tim Riley
Structured Database Models
Three of the many database models are:
* Logical
* Hierarchial
* Relational
©Tim Riley
Logical Database Model
The logical database model supports all 5 relationships:
1) Many-to-one
2) One-to-many
3) Many-to-many
4) One-to-one
5) Is-a
©Tim Riley
Logical Database Model
One fact one place. The logical database model has no
redundancy.
However, no practical database engine has been developed to run the logical
model. Therefore, it is used for database conceptualizing only. Once a logical
model is finished, then redundancies and implementational restrictions are
introduced to convert the logical model to either the hierarchial or relational
model.
©Tim Riley
Hierarchial Database Model
A database engine that runs the hierarchial database
model is very efficient at running one-to-many
relationships.
One-to-many relationships are easy to understand and explain to your
client. You need to start with any set that you can identify a one element.
Then you logically branch out. For example, a tree has one trunk. One
trunk has many branches. One branch has many limbs. One limb has many
leaves. One trunk has many roots. One root has many ...
©Tim Riley
Relational Database Model
A database engine that runs the relational database
model is very efficient at running many-to-one
relationships.
However, many-to-one relationships are difficult to explain to your client.
”Many leaves are contained on one limb. Many limbs are contained on one
branch. Many branches are contained on one trunk.”
©Tim Riley
Relational Database Model
A database engine that runs the relational database
model is very efficient at running many-to-one
relationships.
But the relational model won the database model war. Therefore,
Appaserver runs on a database engine that runs the relational model.
©Tim Riley
Relational Database Model
A database engine that runs the relational database
model is very efficient at running many-to-one
relationships.
The relational model doesn't
support the many-to-many
relationship nor the is-a
relationship.
Many-to-many relationships are
converted into two many-to-one
relationships.
©Tim Riley
One-to-many relationships
are reversed to become
many-to-one.
Appaserver mimicks the is-a
relationship.
Relational Database Model
Foreign key: in a many-to-one relationship, the many
table needs to have as attributes the primary key of the
one table.
This adds redundancy; however, it is necessary.
Person
full_name
street_address
state
text *
text * many
text
state
text *
one
Foreign key is the primary key
of the one table.
©Tim Riley
State
Reside in
Primary key of the
one table.
Foreign Key
Multi-attribute Primary Key
Person
many
full_name
street_address
city
state
City
Reside in
text *
text *
text
text
one
city
state
text *
text *
Appaserver requires the foreign key to have the same attribute names as the
corresponding primary key. Well, most of the time.
©Tim Riley
Foreign Key
Multiple Relationships
Single-attribute Primary Key
State
Person
Reside in
full_name
street_address
reside_state
born_state
text *
text *
text
text
Born in
many
state
text *
one
For multiple relationships to the same table, the foreign key can't have the
same attribute name as the corresponding primary key. If the one table has a
single-attribute primary key, then change each foreign key's name.
©Tim Riley
Foreign Key
Multiple Relationships
Multi-attribute Primary Key
Person
City
Reside in
full_name
street_address
reside_city
reside_state
born_city
born_state
text *
text *
text
text
text
text
Born in
many
city
state
one
If the one table has a multi-attribute primary key,
then Appaserver can't handle it.
©Tim Riley
text *
text *
Foreign Key
Multiple Relationships
Single-attribute Primary Key
Person
City
Reside in
full_name
street_address
reside_city_state
born_city_state
text *
text *
text
text
Born in
many
city_state
state
one
If the one table has a multi-attribute primary key,
then Appaserver requires you to change it to a
single-attribute primary key.
©Tim Riley
text *
text
This implemental
restriction adds
redundancy and
the possibility of a
contradiction.
What is a structured database?
A structured database allows you to create
an information system. You create sets,
attributes, and relationships so that every
change in the organization's state is
captured. This change in state generates a
new instantaneous database. The set of
instantaneous databases is an information
system.
©Tim Riley
What is Appaserver?
RDBMS means relational
database management system.
Currently, Appaserver supports
MySQL and Oracle. Although
MySQL is much faster.
©Tim Riley
What is Appaserver?
Appaserver sends an HTML form to a
browser, optionally through the
secured socket layer.
©Tim Riley
What is Appaserver?
A user fills out the HTML form
requesting to either select, insert,
update, or delete data. However,
depending upon the user's role,
some operations are disallowed.
©Tim Riley
What is Appaserver?
After the user presses the <Submit>
button, the form gets sent to
Appaserver via the common gateway
interface.
©Tim Riley
What is Appaserver?
Appaserver takes the request for
either select, insert, update, or delete
and generates the proper SQL
statement. The SQL statement is
then sent to the RDBMS.
©Tim Riley
What is Appaserver?
After the RDBMS executes the SQL
statement, it sends Appaserver
either the requested rows of data or
a results message.
©Tim Riley
What is Appaserver?
Appaserver then generates the next
logical HTML form and sends it to
the browser.
©Tim Riley
Appaserver is an
Application Server
Structured databases can grow to hundreds of tables.
Each table needs the select, insert, update, and delete
operation. Historically, a developer would have to write
each operation for each table. On the other hand,
Appaserver has a module for each operation. So
development is nothing more than adding tables to the
Appaserver engine.
©Tim Riley
Appaserver is an
Application Server
Appaserver serves a relational database application to a
browser. It knows how to generate the application's
screens because the application's tables and columns
are stored in a database itself. Appaserver has a
database of the database.
©Tim Riley
Appaserver's Database Structure
Is
described
by
Table
table_name
text *
column_name
many
Table is the relational
database synonym for
set.
Column
many
Column is the relational
database synonym for
attribute.
One table can have many columns. And one column can belong to
many tables. (For example, both a person and a tree can have an
age.) Therefore, there is a many-to-many relationship from table to
column.
©Tim Riley
text *
Appaserver's Database Structure
Table
Is
described
by
many
Column
many
”Table” and ”Column” are reserved words. You
can't create tables with these names.
©Tim Riley
Appaserver's Database Structure
Is
described
by
Folder
folder
text *
attribute
many
Appaserver stores tables in the
table called ”Folder.”
©Tim Riley
Attribute
text *
many
Appaserver stores columns
in the table called
”Attribute.”
Appaserver's Database Structure
Folder
folder
Attribute
text *
attribute
Folder_Attribute
Note: from here on all
of the relationships are
assumed to be manyto-one, unless
otherwise noted.
folder
attribute
text *
text *
Since the relational model doesn't support many-to-many
relationships, we need to add a new table with both their
names, and make two many-to-one relationships.
©Tim Riley
text *
Appaserver's Database Structure
Storing Relationships
State
Person
Reside in
Attend
School
One folder can have a
relationship to many
folders.
©Tim Riley
Appaserver's Database Structure
Storing Relationships
Person
Is a
Accountant
©Tim Riley
One folder can be related to
by many folders.
Is a
Teacher
Appaserver's Database Structure
Storing Relationships
Folder
Has relationship
many
many
Therefore, there is a many-to-many relationship from
folder to folder with regard to relationship.
©Tim Riley
Appaserver's Database Structure
Storing Relationships
Folder
Relation
Since the relational model doesn't support many-to-many
relationships, make two many-to-one relationships.
©Tim Riley
What is Appaserver?
Appaserver is an application server that functions as a liason
between a relational database management system and a
browser. It allows a database developer to focus on
conceptualizing the application, not the screens. The developer
uses Appaserver to create the application. The application user
uses Appaserver to run the application. Creating the application
involves inserting the application's tables, columns, and
relations into a database. Appaserver creates screens by
selecting from this database. Appaserver is committed to
preserving relational integrity and element uniqueness.
The critical development activity is categorizing all of the
organization's information into sets.
©Tim Riley