| # Entity Relationship Diagram The Entity Relationship Diagram represents Entity Types for which data must be stored in the Infor LN Application, such as Purchase Orders, Customers and Projects. Entity Types that represent database tables are placed in the diagram. Relationships are drawn between the Entity Types and their graphical representation indicates the cardinality of the relationship (one to one, one to many or many to many) and the relation is optional. Using Decomposed Diagrams you can link another Entity Relationship Diagram to one of the Entity Types in a diagram, thus indicating all the other relationships of that Entity Type. For instance in a diagram created for Purchase Orders, there is an Entity Type for Items. If you would draw all the Entity Types that are linked to the Item Entity, the diagram becomes unreadably big. By linking an Decomposed Diagram of the Item Entity, the Purchase Order Diagram is readable. Entity Relationship Diagram graphical objects
Menu option | Description
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Insert -> Entity Type | Inserts an Entity that represents an object for which you must record information. Select one of the following: Normal; Logical entity type; a meaning to the real world and is comprised of one or more physical entity types Physical entity type; database tables in the Infor applications. Associative; used to link other entity types.
Insert -> Relationship(1:n) | Inserts a relationship between two entity types. The cardinality of the relationship defines the expected number of related occurrences for each of the two entity types
Insert -> Subtype Relationship | Inserts a subtype relationship between two entity types (a subtype and a supertype) that is used to indicate that the supertype’s attribute also apply to (are inherited by) the subtype.
Operations used in Entity Relationship Diagram
Operation | Description
Modify the Type of the Entity Type | Right-click the Entity Type, point to Type. Select one of these options: Normal Associative; an octagon is added inside the graphical object
Link a Decomposed Diagram to the Entity Type | Right-click the Entity Type, select Properties. Link the appropriate Decomposed Diagram to the Entity Type. The Entity Type graphical object is embossed.
Edit/view the Decomposed Diagram linked to the Entity Type | Right-click the Entity Type, select Edit linked ERD.
Link tables to the Entity Type | Right-click the Entity Type, select Tables. Link the appropriate Infor LN tables to the Entity Type. A Linked Tables icon is attached to the Entity Type.
Modify the Type of the (Subtype) Relationship | Right-click the (Subtype) Relationship, point to Type. Select one of these: Free (midpoints can be added) Direct Z-style Horizontal-Vertical Vertical-Horizontal
Modify the cardinality of the Relationship | Right-click the Relationship, point to Cardinality. Select one of these: One to One (midpoints can be added) One to Many Many to Many
Modify the direction of the (Subtype) Relationship | Right-click the (Subtype) Relationship and select Reverse direction.
Add a Midpoint to a (Subtype) Relationship | Right-click the (Subtype) Relationship and select Add Midpoint to change the route of the Relationship. This is only possible if the Type of the Relationship is Free. You can add as many midpoints as required.
Indicate an optional Relationship between two Entity Types | Right-click the Relationship and select one of the following: Optional From To Optional To From A circle is displayed at the end of the Relationship that is indicated as optional.
Add/modify the description on one and/or the other side of the Relationship | Right-click the Entity Type, select Properties. Now add/modify the description From-To or To-From. The descriptions display in the diagram and can be moved around.
相关主题 Graphical objects used in all diagram types Graphical objects used in the Entity Relationship Model Entity Relationship Diagram objects toolbar |