Creating an entity relationship diagram in visio

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

creating an entity relationship diagram in visio

Use crow's foot notations to illustrate the relationship between entities in a crow's foot diagram. Entities are connected by lines, and symbols at either end. How to create a Chen ER Diagram. Open Microsoft Visio (Start -> Programs -> Microsoft Office -> Microsoft Office Visio ); Minimize Visio Window; Link to. It is a common task for a developer to build an Entity Relationship (ER) Diagram for an existing database. If you are dealing with an MS SQL.

This ability is limited to only VisioModeler 2.

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

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. 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. Under Categories, click Definition and type a name for the table.

Under Categories, click Columns, type a name, and choose a data type.

creating an entity relationship diagram in visio

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.

creating an entity relationship diagram in visio

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. 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. 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.

creating an entity relationship diagram in visio

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.

Where is the Entity Relationship Diagram in VISIO ? Please reinstate this in VISIO.

Double-click the table to which you want to add an index, and in the Database Properties window, in the Categories list, click Indexes. In the Create Index dialog box, type a name for the index, and then click OK.

creating an entity relationship diagram in visio

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. 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. Double-click the table or view whose extended properties you want to set, and in the Database Properties window, in the Categories list, click Extended. Create check clauses Use check clauses to ensure that the data that is entered into a column is within a particular range of values.

For example, you can create a check clause that requires the data in a column called "Age" to be over Double-click the table to open the Database Properties window. Under Categories, click Columns and then click the column that you want to add a check clause to.

Since Visioa new feature, Reverse Engineer, has been made available in its Professional edition and Premium edition in Visio This feature allows you to connect to an existing database, extract database schema, and create an ER Diagram automatically.

You can also lay things out in the way that you want, and catch changes made to the database. The key here is to create a connection to your database. It does not have to be a Microsoft database. Most likely, if there is an ODBC Data Source defined on your computer, you can connect to your database in Visio and generate the diagram. The process would be similar for connecting to other types of databases. Usually, you do not have to do this for Access Database. It should have been created when Office or Visio is installed.

For other types of databases, you may need to first install an ODBC Driver which is often available from your database provider. It is important to choose the right template, or you will not see the feature we want to use. Once the file is created, you will see two new things that you normally do not see.