Data modeling is a crucial step in the database development process. It involves designing the structure and relationships of the data that will be stored in a database. In this article, we will explore the concept of data modeling using SQL Server, one of the most popular database management systems.
Step 1: Getting Started with ERWIN
ERWIN is a powerful data modeling tool that allows you to create logical and physical data models. To begin, open ERWIN and select “File” -> “New”. Choose the “Logical/Physical” radio button and click “OK”. Make sure “SQL Server” is selected as the target database.
Next, enable the toolbar by selecting “View” -> “Toolbar” and ensuring all options are selected, including the “Toolbox” option. Click on the “Entity” icon in the toolbox and place it on the designer area. Right-click on the entity icon and select “Entity Properties”. Enter a name for the entity, such as “Employee”, and click “OK”.
Repeat the above steps to create another entity called “Department”. Add attributes to each entity by right-clicking on the entity icon, selecting “Attributes”, and entering the necessary details.
Step 2: Creating Relationships
In data modeling, relationships define how entities are connected to each other. To create a relationship between the “Department” and “Employee” entities, click on the “Non Identifying Relationship” icon in the toolbox. Click on the “Department” entity and then on the “Employee” entity. Click “OK” on the popup that appears.
Double-click on the relationship line/icon and select the “RI Actions” tab. Ensure that “NONE” is selected in all the dropdowns under the “RI Actions” subheading. Click “OK” to save the changes.
Step 3: Converting to Physical Model
Once you have created the logical model, you can convert it into a physical model and generate the necessary SQL code to create the tables in the database. Select “Physical” from the dropdown at the top/center of the window. The diagram and the left pane tree will change accordingly.
Step 4: Generating SQL Code
To generate the SQL code, select “Tools” -> “Forward Engineer” -> “Schema Generation”. In the “Options” tab, choose the desired settings for table creation and column order. Click on “Preview” to see the DDL statements that will be executed in the target database.
Click on “Generate” to let ERWIN create the tables in the database. You may need to provide the database properties and establish a connection. Once the process is complete, you should see the new tables created in your database.
Conclusion
Data modeling is a critical aspect of database development, and tools like ERWIN make it easier to design and maintain complex data models. In this article, we have explored the basics of data modeling using SQL Server and ERWIN. By following these steps, you can create logical and physical models, define relationships, and generate SQL code to create tables in your database.
Remember, data modeling is an extensive topic, and there are many advanced features and techniques to explore. This article serves as a starting point for beginners to understand the fundamentals of data modeling with SQL Server.
Thank you for reading!