In a relational database what is a relationship?

Answer 1

It refers to the connection between two tables. For example, in one table there may be personal details for employees, like name, address, date or birth etc. In another there may be could be payment details for those employees. Their personal details will not appear in that table. In each table there would be one common field, like an employee number. If you know the employee number from the personal details table or the wages table, you can check in the other table and find that number. The details with it relate to the particular person. So even though there name is not in the wages table, you can still find their details, by looking for their employee number. The connection of having an employee number in both tables that can be matched up is a relationship.