Hello world! I'm talking about database design.

In this video we're going to talk about some of the terms that we will be using in database design.

A company database contains all the data that

the company uses to conduct business.

That might include data about customers, employees,

products, orders, supplier, shipments, payroll, and so on.

A well-designed database is crucial to the success of the business.

The process of normalization

Creates a database

That is simple,

Flexible. and not redundant.

That is, each piece of information is in just one place.

A database is organized

into tables.

Each table has information

About one type of entity. or object.

There would be a table for all entities that they keep data on.

Typically a company database would have tables for information about customers,

employees, products, suppliers, orders, etc.

A table

has one record, or row, for each item of that type.

A customer table would have one row, or record,

for each customer.

An employe table

would have one record, or row, for each employee.

A table

has a field for each piece of information.

Fields are also called columns, attributes,

Characteristics, or facts.

An employee table would probably have fields

for the employee ID,

name, department, title,

and salary.

Fields are assigned a data type,

Such as text or string, numeric, date/time, etc.

Keys:

Each table must have one or more fields

That uniquely identify one record in the table.

The employe table might use employee ID has the key.

A customer table might use the customer email as the key.

An invoice table

might user both the supplier ID

And the date as a key.

Here's an example of a database that has tables for

customer, employee, product,

and order.

And the fields in the customer table,

Might include the customer email, as the key,

Their name, address, phone number,

And so on.

Employees would have an employee ID, salary, email,

name, address, phone number.

And products would have a product number, a name,

a supplier, quantity in stock, reorder Point, weight, size,

color, and so on.

An order might have the customers email, product

number, quantity, date, salesman, and so on.

Modern databases

are relational databases.

And relational databases means that

one table can use a key to access information in another table; or relate one table to another table.

And that keeps it from being redundant.

So for instance, an order

Might have one field is the customer email.

And we don't have the customer's name and address here,

Because that customer email relates back to the customer table and we can retrieve all that other information from the customer table. So the customer's name and address is just in one place and if the customer changes his address.

Here.

We don't have it in a different place, a different address.

The same with the product number, I don't have the name of the product or the size and weight and color here.

Because this product number relates to this product table and I can retrieve all the rest of that information,

There.

The salesman even though it's not the same name relates back to the employee and the salesmanm

salesman would be the same as the employee ID and so we could give

credit to that salesman for

making that sale.

We are going to go through all the steps of creating this

Relational database that is normalized to make it flexible, simple,

And non-redundant.

And that's it for now.