Important Terms Related to Database Normalization
Entity: It is basically a set of the objects which are appropriate for the creation of the database. Whatever information you dwelling into the entity must appear in a tabular form. For instance, if the entity is created for an employee, then all the employee's name will be mentioned in that table.
Attribute: The descriptive explanation or characteristics of the entity will be described in the section of attributes. You can say the features of an entity is explained as an attribute. For the above example of Employee- the name & Identification card of the user is called an attribute. You can define like this for making your database; Employee_ID, Employee_Name.
Primary Key: It is a key which is used to uniquely define the entity. It is a key which distinct from one employee to another. If you look closely, the name of two employees can be the same but the identification number is surely different. Thus, you can use this as a primary key in the database for distinguishing one person to another.
Relationship: The logical link is maintained between two and more entities which are called relationship. The foremost entity is called the Parent entity which has several subdivisions, whereas subdivision entities are called a Child entity. The relationship between entities can be of many forms, such as:
- One-To-One: In this kind of relationship, there is one child and one parent. This type of relationship must be avoided as it leads to higher complexity and redundancy.
- One-To-Many: The relationship is formed from one single entity to several subparts. That means there are only one parent entity and several child entities.
- Many-To-Many: in this case, there could be many parent entities as well as many child entities. The database which is designed to handle huge data basically uses this kind of relationship to manage the data.
Foreign Key: Foreign key is just similar to the primary key where it is used to uniquely identify the entities from one to another. The only difference is that It is defined in the second table where the primary key is defined within the first table. For instance, if there are two relational databases which are having employee identification column, then you can distinguish them with the help of Foreign key. For alternative tables, you can go for foreign key, otherwise, for the single table, you can choose the primary key only.
Identifying & Non-Identifying: identifying Relationship resides in the database when the parent entity primary key is included in the child key primary key. However, in the non-identifying relationship, the definition is somewhat changed. As in this, the parent entity primary key can be included in the child entity but it can’t be used as the part of a child’s primary key. Furthermore, the value of the entity of the child can’t be considered as null. It is a non-identifying as well as the mandatory field.
Now you are clear with the basic terms, let us explore the normal forms of database. It helps will help to understand how the data is fetched. To get complete information on this topic, you can also attain database normalization report writing services.
Database Normal Forms:
First Normal Form (1NF)
In this, each table of the database must have only one single value. Plus, the record of each row and column must be unique. Have a look at the below table:
Second Normal Form (2NF)
It should be present in the 1NF. Secondly, the single column must have a primary key.
In this table, the 1NF table is segregated into two tables where the first table contains the information of the members and the second table consist of the information of movies rented.
Third Normal Form (3NF)
It should be in the 2NF and should not have any transitive functional dependencies. Look out the table below
Boyce-Code Normal Form (BCNF)
The third normal could have redundancies in it, thus it is advisable to use BCNF.
Fourth Normal Form (4NF)
If there is no database which is consisting of more than two multivalued and independent data, then it will be considered in the fourth normal form. You can hire the database normalization assignment help to understand the concepts of 4N form.
Fifth Normal Form (5NF)
If it is in Fourth normal form and it can’t be decomposed further into smaller parts without data loss, then it is called a fifth normal form.
Sixth Normal Form (6NF)
This form is not standardized. Though it has been discussing by the database experts, yet there is no clear definition till now. Hope we will get in the coming future.
Students may need database normalization case study writing help to understand the above concepts in a more concise way.