Topic: ER diagram of Library Management System
ER Diagram is known as Entity-Relationship Diagram, it is used to analyze the structure of the Database. It shows relationships between entities and their attributes. An ER model provides a means of communication.
The Library Management System database keeps track of readers with the following considerations –
- The system keeps track of the staff with a single-point authentication system comprising login Id and password.
- Staff maintains the book catalog with its ISBN, Book title, price(in INR), category(novel, general, story), edition, author Number, and details.
- A publisher has the publisher Id, the Year when the book was published, and the name of the book.
- Readers are registered with their user_id, email, name (first name, last name), Phone no (multiple entries allowed), and communication address. The staff keeps track of readers.
- Readers can return/reserve books that are stamped with the issue date and return date. If not returned within the prescribed time period, it may have a due date too.
- Staff also generate reports that have readers id, registration no of report, book no and return/issue info.
Example 1: ER diagram of Library Management System
As it can be observed in this example, the entities are present with their attributes. At the same time, the direct relations between the attributes are also shown, such as several CDs and books are present, so to differentiate, they have specific ISBNs and ISSNs. One key element to understand here is that proper symbols are used to understand an entity diagram.
Example 2: ER diagram of Library Management System
Here is a straightforward ER diagram for the Library Management System. You can observe the entity relations quite clearly, and their attributes are evident as well.
Problems with Building an ER diagram of Library Management System
ER diagrams are usually used to resolve some sort of issue and so they always have a certain problem to solve. Some of the problems that can arise in a Library Management System are as follows:
- A single student can borrow or subscribe to multiple books, which means a one-to-many relationship needs to exist between both these entities.
- A student can later become a member once they have paid a fee, so there should be space in the ER diagram for up-gradation between these entities.
- It would be best if you were varying that every book in the library is identified with a different ID. This means it will create an extensive database, and a comprehensive ER diagram needs to be in place.
- In a library, multiple members or students enroll themselves. These require a unique ID to identify them properly.
- When issuing books, there needs to be a due date set in place to return that book, which requires another addition in the ER Diagram.
Entities and their Attributes –
- Book Entity: It has authno, isbn number, title, edition, category, and price. ISBN is the Primary Key for Book Entity.
- Reader Entity: It has UserId, Email, address, phone no, and name. Name is a composite attribute of first name and last name. Phone no is multi-valued attribute. UserId is the Primary Key for the Readers entity.
- Publisher Entity: It has PublisherId, Year of publication, and name. PublisherID is the Primary Key.
- Authentication System Entity: It has login id and password with LoginID as the Primary Key.
- Reports Entity: It has UserId, Reg_no, Book_no, Issue/Return date. Reg_no is the Primary Key of reports entity.
- Staff Entity: It has name and staff_id with staff_id as the Primary Key.
- Reserve/Return Relationship Set: It has three attributes: Reserve date, Due date, Return date.
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