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Let us understand the concept of One-to-One relationship with the help of example.
Person Table
PersonID Name Age Address
(Primary Key)
1 Yash 30 Delhi
2 Mehul 28 Meerut
3 Varun 32 Delhi
4 Neetu 31 Kanpur
Passport Table
PassportID PassportNumber ExpiryDate PersonID
(Primary Key) (Foreign Key)
101 A12345 2026-05-15 1
102 B67890 2027-03-20 2
103 A25689 2026-05-15 3
104 C25874 2027-03-20 4
In the given relationship, each person has exactly one passport, and each passport belongs to exactly one person. So,
the relationship between Person and Passport tables is one-to-one.
• One-to-Many: This is one of the most common types of relationship between the tables in a database. In this
type “Each record of Master table is related to multiple Records of Transaction table.” It is represented as a 1:n
relationship.
Let us understand the concept of One-to-Many relationship with the help of example.
Department Table
DeptID (Primary DeptName Location
Key)
1 Engineering Sonipat
2 Marketing Meerut
3 Sales Delhi
Employee Table
EmployeeID Name DeptID
(Primary Key) (Foreign Key)
101 Yash 1
102 Mehul 1
103 Varun 2
104 Neetu 3
105 Nisha 2
In the given relationship, each department can have many employees, but each employee belongs to only one
department. So, the relationship between Department and Employee tables is One-to-Many.
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