Скачать или смотреть Achieving DataTable Expressions Across Multiple Tables in C#

Discover how to perform cross-`DataTable` calculations in C- without merging tables. Learn effective techniques and explore alternatives for expressing complex logic with DataSets.
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Dealing with Multiple DataTables in C-

When working with data in C-, it’s common to want to perform operations across multiple DataTables. If you've ever needed to reference columns from different DataTables to create new calculated fields, you may have run into a challenge.

In this guide, we will explore the problem of referencing columns across two separate DataTables, and how to achieve this without merging them. We'll show you how to use a DataSet to facilitate this process, along with a code example that illustrates the solution.

The Problem

Imagine you have two DataTables, DT1 and DT2.

DT1 contains columns A1, B1

DT2 contains columns A2, B2

Your goal is to assign a value to column A1 in DT1 that is computed from values in DT2, specifically the expression A1 = A2 + B2.

Key Questions

Is it possible to perform this operation without merging or joining the two DataTables?

Are there alternative data structures or techniques that can achieve this?

The Solution

Using a DataSet

While a DataTable alone doesn't support direct cross-referencing of columns from other tables, we can utilize a DataSet to help organize your DataTables. Here's how:

Add Both DataTables to a DataSet:
Create a DataSet that contains both DT1 and DT2.

Perform Calculations Using DataRows:
Iterate through each row in DT1, find the matching row in DT2, and perform the calculation.

Implementation Steps

Here's a sample code snippet demonstrating how to implement this solution:

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

Explanation of the Code

DataTable and DataSet Creation: We first create two DataTables, dt1 and dt2, adding necessary columns to both. Then, we put these tables together in a DataSet.

Iterating Through Rows: The main logic happens in the foreach loop. We iterate through each row of dt1:

We find the matching row from dt2 based on a common identifier ID.

We then calculate the value for A1 by summing A2 and B2 from the matched row in dt2.

Additional Considerations

This example uses addition for clarity, but you can extend it to include other mathematical and logical operations depending on your requirements.

DataSets provide a flexible approach for handling multiple DataTables, allowing you to manage complex relationships without sacrificing performance.

Conclusion

While it may seem complex to reference columns across separate DataTables in C-, utilizing a DataSet can simplify your data handling. By implementing the above technique, you can efficiently compute values based on data from different tables without the need for merging.

If you have more scenarios or need further examples on data handling in C-, feel free to ask in the comments!