Reader: (serial number), name.

Borrowing: (book number), (reader number), borrowing date.

Reader-borrowing1:n. As shown:

There are four components in the ER diagram:

Rectangular box: represents an entity, and the entity name is recorded in the box.

Diamond box: indicates the contact person, and the name of the contact person is recorded in the box.

Oval box: indicates the attribute of an entity or contact, and records the attribute name in the box. Please underline the main attribute name.

Connection: between entity and attribute; Between entity and contact; Connections and attributes are connected by a straight line, and the type of connection is marked on the straight line. (One-to-one contact, the connection direction of two entities is written as1; One-to-many contact, write 1 on one side and n on the other; For many-to-many relationships, n and m should be written in the connection direction of two entities. )

Extended data:

When using, click the "Borrow" button or press enter directly, and the cursor is positioned in the item "Borrower's code or name".

After entering the borrower's code or name, the system will automatically judge. If there is no record of the borrower in the borrower database of the system, the system will give a prompt;

Click the "Return Book" option or press Enter directly, and the cursor will be positioned in the item "Borrower's code or name".

After entering the code or name of the borrower and the code of the borrowed book, the system will automatically judge. If there is no borrowing information of this person in the system, the system will prompt the user; If this person's borrowing information does exist in the system library, the system reads the borrowing information from the database and fills it in the borrowing window. At the same time, the system also writes the librarian information and the book return date into this window.

Baidu Encyclopedia-Book Management System