Structured Database Running on Appaserver ©Tim Riley What is a structured database? What is Appaserver?

Structured Database Running on Appaserver

©Tim Riley

What is a structured database?

What is Appaserver?

What is a structured database?

Unstructured database:

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.

Do this better than Google, and you'll become a billionaire.

©Tim Riley

What is a structured database?

Unstructured database:Structured database:

In a structured database, a specialist categorizes all of the organization's information into sets.

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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.

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What is a structured database?

Set Name

Database sets are also known as:* categories* tables* folders* collections

Represent database sets in rectangles, with the set name above the title line.

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What is a structured database?

Set Name

Attribute 1 datatypeAttribute 2 datatype …Attribute n datatype

Describe set characteristics with attributes. Attributes are used to divide a set into many subsets.

Attributes are also known as:* columns* fields* properties

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What is a structured database?

Set Name

Attribute 1 datatypeAttribute 2 datatype …Attribute n datatype

Each attribute is assigned a datatype. Examples of datatypes:* Integer number* Floating point (real) number* Date* Time* Line of text* Notepad of text

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Example Set

Personfull_name textskin_color textreligion textheight_inches integerweight_pounds integerbirth_date dateannual_income floatgeneral_characterists notepad

These attributes help describe a person.

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Set Elements

PersonFull Name

Linus Torvalds

Guido van Rossum

Bill Henry Gates III

There are 3 elements in the person set.

Sets contain elementsSet elements are also known as:* Members* Tuples* Rows* Objects* Records

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Making Subsets

Personfull_name textskin_color textreligion textheight_inches integerweight_pounds integerbirth_date dateannual_income floatgeneral_characterists notepad

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.

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Set Relationships

Sets are related to other sets. Set relationships are identified using verbs.

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Set 1 Set 2Verb phrase

Set Relationships

Person

Sets are related to other sets. Set relationships are identified using verbs.

StateReside in

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Many Set Relationships

One set can be related to more than one set.

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Person StateReside in

School

Attend

Many Set Relationships

One set can be related to another set twice, three times, etc.

Person StateReside in

Born in

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Set Relationship TypesSet 1

There are 5 types of set relationships:* many-to-one* one-to-many* many-to-many* one-to-one* is-a

Set 2Verb phrase

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Many-to-one RelationshipPerson

”Many persons

StateReside in

many one

one state.”reside in

Therefore, there is a many-to-one relationship from person to state with regard to residence.

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One-to-many RelationshipPerson

Reverse the arrow to reverse the relationship. ”One state has as residents many persons.”

StateHas resident

many one

Therefore, there is a one-to-many relationship from state to person with regard to residence.

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Many-to-many RelationshipPerson

”One person can visit many states. And one state can have as visitors many persons.”

StateVisit

many many

Therefore, there is a many-to-many relationship from person to state with regard to visitation.

If you have a one-to-many relationship going both ways, then you have a many-to-many relationship.

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Many-to-many relationships can go both ways. ”Therefore, there is a many-to-many relationship from state to person with regard to visitation.”

One-to-one RelationshipOffice

”One office has one phone.”

PhoneHas

one one

Therefore, there is a one-to-one relationship from office to phone.

One-to-one relationships are rare. More often than not, you would move the attributes of phone over to the office category.

One-to-one relationships can go both ways. ”One phone can be located in only one office.”

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Is-a RelationshipAccountant

”An accountant is a person.”

PersonIs a

one one

Therefore, there is an is-a relationship from accountant to person.

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.

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Enforcing Business Rules

Two broad categories of business rule enforcement are:

* Implementational restrictions (bad)* Integrity constraints (good)

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Enforcing Business Rules

Implementational restrictions are business rules the information system cannot enforce.

Person StateReside in

many one

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.

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Enforcing Business RulesIntegrity constraints are business rules the information system succeeds at enforcing. Two imperative integrity constraints are:

* Relational integrity* Element uniqueness

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Enforcing Business RulesRelational integrity is the constraint that an element in each set must exist in order for a relationship to exist between them.

Person StateReside in

many one

A state can exist without any persons residing in it.

A person can exist without residing in a state.

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.

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Enforcing Business RulesElement uniqueness is the constraint that an element cannot exist more than once in a set.

Personfull_name text *

Only one person named Bill Henry Gates III can belong to the person set.

To show that an attribute has been assigned to the set of attributes enforcing uniqueness, append an asterisk.

The set of attributes enforcing uniqueness is called the primary key.

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Element UniquenessNatural primary key: the set of attributes that naturally enforce uniqueness.

Personfull_name text *street_address text *

Names are likely to be naturally duplicated.

Therefore, assign the street address (a place) as an additional attribute to the primary key.

If a set has more than one attribute assigned to its primary key, then it's called a multi-attribute primary key.

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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) Longitude2) Latitude3) Elevation4) Time

All of the organization's places should be categorized.

All events need a date/time stamp.

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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.

Surrogate primary keys are badbad 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.

Consider auditing transactions with customer numbers, sales-representative numbers, store numbers, and transaction codes. Sheesh!

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Element UniquenessMutable primary keys: The value of primary keys can change when using Appaserver.

Personfull_name text *street_address 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.

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Structured Database Models

Three of the many database models are:* Logical* Hierarchial* Relational

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Logical Database Model

The logical database model supports all 5 relationships:

1) Many-to-one2) One-to-many3) Many-to-many4) One-to-one5) Is-a

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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.

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Hierarchial Database ModelA 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 ...

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Relational Database ModelA 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.”

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Relational Database ModelA 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 ModelA 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.

One-to-many relationships are reversed to become many-to-one.

Many-to-many relationships are converted into two many-to-one relationships.

Appaserver mimicks the is-a relationship.

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Relational Database ModelForeign 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.

Personfull_name text *street_address text *state text

Statestate text *

Reside in

many one

Foreign key is the primary key of the one table.

Primary key of the one table.

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Foreign KeyMulti-attribute Primary Key

Person

full_name text *street_address text *city textstate text

City

city text *state text *

Reside in

many one

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Appaserver requires the foreign key to have the same attribute names as the corresponding primary key. Well, most of the time.

Foreign KeyMultiple Relationships

Single-attribute Primary KeyPerson

full_name text *street_address text *reside_state textborn_state text

State

state text *

Reside in

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Born in

many 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.

Foreign KeyMultiple Relationships

Multi-attribute Primary KeyPerson

full_name text *street_address text *reside_city textreside_state textborn_city textborn_state text

City

city text *state text *

Reside in

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Born in

many one

If the one table has a multi-attribute primary key, then Appaserver can't handle it.

Foreign KeyMultiple Relationships

Single-attribute Primary KeyPerson

full_name text *street_address text *reside_city_state textborn_city_state text

City

city_state text *state text

Reside in

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Born in

many one

If the one table has a multi-attribute primary key, then Appaserver requires you to change it to a single-attribute primary key.

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.

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What is Appaserver?

RDBMS means relational database management system.Currently, Appaserver supports MySQL and Oracle. Although MySQL is much faster.

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What is Appaserver?Appaserver sends an HTML form to a browser, optionally through the secured socket layer.

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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.

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What is Appaserver?After the user presses the <Submit> button, the form gets sent to Appaserver via the common gateway interface.

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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.

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What is Appaserver?

After the RDBMS executes the SQL statement, it sends Appaserver either the requested rows of data or a results message.

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What is Appaserver?

Appaserver then generates the next logical HTML form and sends it to the browser.

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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.

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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.

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Appaserver's Database Structure

Tabletable_name text *

Columncolumn_name text *

Is described

by

many many

Table is the relational database synonym for set.

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.

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Table ColumnIs

described by

many many

”Table” and ”Column” are reserved words. You can't create tables with these names.

Appaserver's Database Structure

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Appaserver's Database Structure

Folderfolder text *

Attributeattribute text *

Is described

by

many many

Appaserver stores tables in the table called ”Folder.”

Appaserver stores columns in the table called ”Attribute.”

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Appaserver's Database StructureFolder

folder text *

Attributeattribute 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.

Folder_Attributefolder text *attribute text *

Note: from here on all of the relationships are assumed to be many-to-one, unless otherwise noted.

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Appaserver's Database Structure

Storing Relationships

Person

StateReside in

One folder can have a relationship to many folders.

SchoolAttend

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Appaserver's Database Structure

Storing Relationships

PersonOne folder can be related to by many folders.

Accountant Teacher

Is aIs a

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Appaserver's Database Structure

Storing Relationships

Folder Has relationship

Therefore, there is a many-to-many relationship from folder to folder with regard to relationship.

many

many

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Appaserver's Database Structure

Storing Relationships

Folder

Since the relational model doesn't support many-to-many relationships, make two many-to-one relationships.

Relation

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What is Appaserver?

©Tim Riley

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.