Listen Software Solution "How to" Series 1: Paradigm
General rule
The following paradigm usually means dividing the table into two or more tables at a few columns, and the primary key is designed in a smaller table. Therefore, they can be reconnected by the Join operator. The advantage of the segmentation table is to reduce data redundancy.
The following is a brief overview of the standard paradigm:
First paradigm
For each row in the table, there must be only a unique row value. There is only a unique value in each column in a row and has atomic.
Second paradigm
The second paradigm requires non-main key columns to be the subset of primary keys, and non-primary key column must completely depend on the entire primary key. The primary key must have a unique element, and a primary key can consist of one or more columns that make up a unique value. Once created, the primary key cannot be changed, the foreign key is associated with the primary key of a table. The primary key association means a pair of relationships.
Third paradigm
The third paradigm requires non-main key columns to do not depend on each other.
Fourth paradigm
The fourth paradigm is prohibited from main key columns and non-main key columns.
Fifth paradigm
The fifth paradigm divides the table into small pieces as small as possible, in order to exclude all redundancy in the table.
(to be continued)
