How to Make a DataGridView CellValueChange in VB.NET: Updating Two Columns Automatically

Discover how to efficiently update two columns in a DataGridView using VB.NET, streamlining your sales order application with real-time data from your database.
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Automating Cell Updates in a DataGridView with VB.NET

When developing applications that require user input, such as a sales order system, having a responsive and intuitive interface is crucial. One common requirement is automatically updating related fields in a data grid when a user interacts with specific cells. For instance, you may want to update an item's description based on its code and vice versa. This can become challenging, especially when database connections and data retrieval are involved. Let's explore how to achieve this in VB.NET.

The Problem

You are developing a sales order application using a DataGridView with the following columns:

ItemCode

ItemDescription (as a ComboBox)

Quantity

Price

Your goal is twofold:

When a user inputs an ItemCode, the corresponding ItemDescription should automatically populate from the database.

Conversely, if a user selects an ItemDescription from the ComboBox, it should update the ItemCode.

You initially encountered issues with your implementation, specifically receiving an error stating, "The Connection was not closed." Let's look at a refined solution.

Enhancing Your Code

Here's an updated approach that addresses common programming pitfalls, improves efficiency, and ensures secure database interactions.

Best Practices to Follow

Use Narrow Scopes for ADO.NET Objects: Always create your database connection, command, and reader objects within the narrowest scope possible to avoid lingering connections.

Retrieve Only Necessary Data: Instead of using SELECT *, focus on selecting only the columns you need. In this case, querying a single column for either the code or description.

Utilize Parameters in SQL Queries: This helps in preventing SQL injection attacks and ensures that your queries remain secure.

Avoid Code Duplication: Utilize functions to extract repetitive code patterns, focusing on clarity and maintainability.

Refactored Code

Here is the refactored code that implements these best practices:

[[See Video to Reveal this Text or Code Snippet]]

An Alternative Approach: Binding Data

Instead of querying the database each time a user makes an entry, consider loading all relevant data at the start and using a BindingSource. Here’s a condensed version of how this could look:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By breaking down your implementation into clear, organized sections and utilizing the best practices highlighted, your application can effectively handle two-way updates within a DataGridView. Automating these updates not only enhances user experience but also simplifies the data entry process.

Make sure to thoroughly test your implementation to guarantee a seamless integration into your sales order system. Happy coding!