The SERM (structured entity relationship model) is an amplification of the ERM which is commonly used for

data modeling Data modeling in software engineering is the process of creating a data model for an information system by applying certain formal techniques. Overview Data modeling is a process used to define and analyze data requirements needed to suppo ...

. It was first proposed from Prof. Dr. Elmar J. Sinz in 1988. The SERM is commonly used in the

SAP Sap is a fluid transported in xylem cells (vessel elements or tracheids) or phloem sieve tube elements of a plant. These cells transport water and nutrients throughout the plant. Sap is distinct from latex, resin, or cell sap; it is a separa ...

-world for the

Aims

# structuring of large schemes # visualization of existence dependency # avoidance of inconsistencies # avoidance of unnecessary relationshiptypes

SERM symbols

SERM example

* Customer and article are independent entities * Every order is referred to one customer. Orders without customers are illegal (order is an ER type). Customers without any orders are legal because they are independent Entities. * To every order there is belonging at least one order item. * Every order item is related to exactly one order. * Every invoice is referred to one customer, as well. Invoices without customers are illegal. Customers without any invoice are legal. * To every invoice there is belonging at least one invoice line item. * Every invoice line item is related to exactly order item. An order item could be calculated or not. * SERM is already in the

third normal form Third normal form (3NF) is a database schema design approach for relational databases which uses normalizing principles to reduce the duplication of data, avoid data anomalies, ensure referential integrity, and simplify data management. It was de ...

References

{{reflist Data modeling Diagrams Modeling languages