Structuring Database for Accounting

debit account(s) and vouchers contain credit account(s). In ER Model, these references are represented as explicit relationships rather than attributes. (i) Types of relationships : Whenever entities from different entity types are related to one another in a particular manner, they constitute a relationship type. The relationship prepared by between the two entity types vouchers and employees associates each voucher with the employee who prepared it.

Similarly, the relationship authorised by between the two entity types vouchers and employees associates each voucher with the employee who authorises it. Each relationship instance of prepared by (short named as PrepBy ) associates one voucher entity with one employee entity. In ER diagrams, relationship types are displayed as diamond shaped boxes, connected by straight lines to the rectangular boxes, which represent the participating entity types. Fig.

. : Diagram showing binary relationship between vouchers and employees (ii) Degree : The degree of a relationship type is the number of participating entity types. A relationship type of degree two is called binary and that of degree three is called ternary. A VOUCHER (entity),