This is an introduction to relational database design principles without the use of daunting language.
There are a number of principles that should be followed when designing the structure of relational data. They are designed to ensure integrity, avoid redundancy, and support future changes to your data.
They can seem a little overwhelming at first. As you work with the principles, you will find them to be common-sense and extremely helpful when working with data.
Each column should contain a single value.
Each column in your database should contain a single value. You should not have multiple values in a single cell.
Every value in a column should be of the same type.
Within a column, every value should be of the same type of information. You should not mix the type of information within a column.
Each record should be unique.
Each record in your database should be unique. You should not have more than one record containing the same data.
Each piece of data should only be stored in one place.
Each piece of data in your database should only be stored in one place. You should not store the same information in more than one place.
The order of records in a table should not carry any meaning.
The order of records should not be used to indicate any meaning about the data. If it is necessary to indicate the order, use a column to record it.
Each table should have a Primary Key (PK) that is unique for each record.
Each table in your database should have a unique column as a primary key. This can then be used to accurately identify each record, and refer to those records from another table.
The Primary Key (PK) should not carry any meaning, other than uniquely identifying each record.
The Primary Key should not carry any meaning other than uniquely identifying each record. It should never be used for any other purpose.
Each table should describe a single entity.
Each table in the database should describe a single logical entity. You should not mix entities within the same table. Every column in a table should relate directly to that entity.
Your email address will not be published. Required fields are marked *