How to create a object relationship diagram

Creating object model diagrams

how to create a object relationship diagram

Before you create a class diagram, you might create an object diagram to An object diagram shows this relation between the instantiated classes and the. You can use Object model diagrams to specify the structure and the static relationships of the classes in a model. In UML, object diagrams provide a snapshot of the instances in a system and the However, while class diagrams show the actual classifiers and their relationships in a You can create object diagrams by instantiating the classifiers in class.

Select whether you want the reverse engineered items to be added automatically to the current page. You can choose to have the wizard automatically create the drawing, in addition to listing the reverse engineered items in the Tables and Views window. If you decide not to have the drawing created automatically, you can drag the items from the Tables and Views window onto your drawing page to manually assemble the database model. Review your selections to verify that you are extracting the information that you want, and then click Finish.

The wizard extracts the selected information and displays notes about the extraction process in the Output window. This ability is limited to only VisioModeler 2. On the Database tab, in the Model group, click Import, and then click the model type.

Type the path and file name for the model that you want to import, or click the Browse button to locate the model file, and then click Open. In the Import dialog box, click OK.

Visio imports the file and displays its progress in the Output window. The imported tables are displayed in the Tables and Views window.

Create a Database Model (also known as Entity Relationship diagram) - Visio

In the Tables and Views window, select the tables that you want to model, and then drag them onto the drawing page. After you create a database model diagram, the work of refining the diagram begins. You can add and customize tables and views, create relationships, and customize columns and data types.

Tables Use the Entity shape to create a table in your diagram. From either the Entity Relationship or Object Relational stencil, drag an Entity shape onto the drawing. Double-click the shape to open the Database Properties window.

how to create a object relationship diagram

Under Categories, click Definition and type a name for the table. Under Categories, click Columns, type a name, and choose a data type. Select the Req'd check box for columns that can't have null values.

Select the PK primary key check box for columns that uniquely identify each row in the database table. Columns Use the Database Properties window to add or change properties for columns, including data types and primary keys. Double-click the table in your diagram. In the Database Properties window, under Categories, click Columns.

Click in the first empty Physical Name cell, and type a name. To change the data type for a column, click the column's Data Type field, and then select a data type from the list or type it into the list. For example, you can type decimal 8,2 or char To prevent null values, select the Req'd check box. To specify that the column is a primary key, select the PK check box.

To see more column properties in addition to those that appear when you click the Columns category, select the column and then click Edit. Relationships Relationships use primary and foreign keys to allow databases to match a row in one table with a row in a related table. You can show those relationships in your diagram. In addition, you can set their cardinality for example, one-to-many and use either Crow's feet, Relational, or IDEF1X notation to show the cardinality.

You can't show many-to-many relationships with any of these notations in the Database Model Diagram template. Create a relationship between tables: Make sure that both tables are visible in the diagram. If you reverse engineered the model from an existing database, you may need to drag one or both from the Tables and Views window onto the drawing page. Double-click the table that you want for the primary key side of the relationship.

In the grid, click the column that you want to use to uniquely identify each row in the table, and select the PK check box to set it as the primary key. From the Object Relational or Entity Relationship stencil, drag a Relationship shape and drop it onto a blank space on the page. Connect the higher end to the table with the parent table.

how to create a object relationship diagram

Connect the other end to the child table. If the second table doesn't already contain a column with the same name as the primary key, the modeler adds it to the second table as a foreign key. If relationship lines disappear, on the Database tab, in the Manage group, click Display Options.

how to create a object relationship diagram

On the Relationships tab, under Show, select the Relationships check box. Set the relationship's cardinality: In the Database Properties window, under Categories, click Miscellaneous. Under Cardinality, choose the cardinality that best fits the relationship. For one-to-many relationships, the best choice is either Zero or more or One or more.

For one-to-one relationships, the best choice is either Zero or one or Exactly one. To make other refinements to your diagram such as creating indexes, check clauses, and triggers you can do the following: Create indexes Indexes improve the performance, or speed, of your database when you run a query. Open the database model diagram. Double-click the table to which you want to add an index, and in the Database Properties window, in the Categories list, click Indexes.

Object diagrams

In the Create Index dialog box, type a name for the index, and then click OK. In the Index Type list, select an option to create a unique or non-unique index. In the Indexed Columns list, select the Asc check box to create an index that has an ascending sort order, or clear the check box to create an index that has a descending sort order.

The database model diagram is updated.

how to create a object relationship diagram

Create views You can think of a view as a saved query. Views are particularly handy if you need to repeatedly access the same information from multiple tables, or if you want to expose the data to users without letting them change the actual tables. Set extended properties for tables and views Depending on your database management system DBMSyou may be able to set extended properties for tables or views to determine where they are stored.

You can draw a link while using the lines utilized in class diagrams. Object Diagram In UML, object diagrams provide a snapshot of the instances in a system and the relationships between the instances.

how to create a object relationship diagram

By instantiating the model elements in a class diagram, you can explore the behavior of a system at a point in time. An object diagram is a UML structural diagram that shows the instances of the classifiers in models. Object diagrams use notation that is similar to that used in class diagrams. Class diagrams show the actual classifiers and their relationships in a system Object diagrams show specific instances of those classifiers and the links between those instances at a point in time.

You can create object diagrams by instantiating the classifiers in class, deployment, component, and use-case diagrams. An object diagram must be a valid instantiation of a static class diagram. Objects must have classes and links between objects must be instances of associations between classes. This can be used as a quick consistency check. To do this we can develop an object diagram by using the following steps: Identify the mechanism you'd like to model.

A mechanism represents some functions or behaviors of the part of the system you are modeling that results from the interaction of a society of classes, interfaces, and other things. For each mechanism, identify the classes, interfaces, and other elements that participate in this collaboration; identify the relationships among these things, as well.

Consider one scenario that walks through this mechanism. Freeze that scenario at a moment in time, and render each object that participates in the mechanism. Expose the state and attribute values of each such object, as necessary, to understand the scenario. As this figure indicates, one object represents the robot itself r, an instance of Robotand r is currently in the state marked moving.

This object has a link to w, an instance of World, which represents an abstraction of the robot's world model. This object has a link to a multiple objects that consists of instances of Element, which represent entities that the robot has identified but not yet assigned in its world view. These elements are marked as part of the robot's global state. At this moment in time, w is linked to two instances of Area.