Explain how normal form relations impact database

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Data Consistency

Refers to the usability of data

Advantages:

Clears out redundancies

Design of a complete data system that shows how data from different tables relate to each other

Facilitates the recognition of data connection

Corrects inconsistencies in the database

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Forms

A form is a window that contains numerous fields or spaces to enter data

Any user who views the form gets an idea of its content

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Reports

The formatted result of database queries

Contains useful data decision-making and analysis

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Queries

A request for data or information from a database table

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Relationship Links

There are three types of relationship links in a database:

One to one

One to many/many to one

Many to many

One to one

Child table primary key is associated with the parent table primary key via the foreign key

One to many

Associates a row from the parent table to multiple rows in a child table

They are linked based on a foreign key column...

... in which the child references the primary key of the parent table

Many to many

requires a link table containing two foreign key columns...

references two different parent tables

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Enforcing Referential Integrity

A database concept...

... Ensures that relationships between tables remain constant

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Updates or Deletions

Updates

To change data or files in a database

To upgrade software to a new one

Deletion

The DELETE statement removes one or more records from a table

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Foreign Key

a field in a relational table that matches the primary key column of another table

can be used to cross-reference tables

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Data Validation

checking the accuracy and quality of source data before processing data

There are seven methods of validation: type, presence, unique identifier, range, format, restricted data, referential integrity

Type:

provides an extra type check to ensure invalid data is not entered into the field

Presence:

compels users to enter data into the required fields

Unique Identifier

checks to ensure that a value is entered once in a field

Range Check

ensures that only numbers within a certain domain entered in a field

Format

used for a field that requires an entry in a specific format

Restricted Choice

Fields that have a definite amount of data that can be entered into them

Referential Integrity

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Data Verification

checks that data from the original source document is exactly the same as the data entered into the system

There are two main methods of verification: double-entry, proofreading data

Double - entry

entering data twice and comparing the two copies

Proofreading data

involves someone checking the data entered against the original document

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