Merging Two CSV Files with PowerShell

Learn how to efficiently merge two CSV files in PowerShell by matching columns and exporting the results in a new file.
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Merging Two CSV Files with PowerShell: A Step-by-Step Guide

When working with data management, it's common to find yourself needing to merge multiple CSV files. This task might seem daunting, especially if you're not an expert in PowerShell scripting. In this post, we’ll break down a common scenario where you need to merge two CSV files by matching specific columns—a process that can enhance your data management skills.

The Problem

You want to merge two CSV files where:

CSV1 contains user information with the following columns:

SAMAccountName

mail

Example data:

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

CSV2 includes additional user details but also features a Mail column which should match the mail column in CSV1.

Example data:

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

Your goal is to create a new CSV file (CSV3) that includes all columns from CSV2 and adds the SAMAccountName from CSV1 wherever the emails match.

The Solution

Here, we will walk through a PowerShell script that accomplishes this task, providing both clarity and efficiency.

Required Script

The PowerShell script can be broken down into a series of steps, which I'll outline here along with a complete script.

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

Explanation of the Script

Loading the CSV Files:

The first two lines import the CSV files into PowerShell variables $csv1 and $csv2.

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

Iterating Through CSV2:

The foreach loop iterates over each record in the $csv2 dataset. This is where we compare each record against $csv1 to find matches based on the Mail column.

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

Finding Matches:

The Where-Object command is used to find records in $csv1 where the value of Mail matches the current record’s Mail from $csv2.

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

Creating New Output:

The Select-Object cmdlet is used to create a new object that contains all original properties from $csv2 plus the SAMAccountName from the matched record in $csv1.

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

Exporting the Result:

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

Troubleshooting Tips

Ensure that the column names match precisely, including case-sensitivity.

If the resulting SAMAccountName column is still blank, check for any leading or trailing spaces in the Mail addresses.

Confirm that both CSV files are correctly formatted and that there are no corrupt or blank entries.

Conclusion

Merging CSV files using PowerShell can streamline your workflow and improve data accuracy and efficiency. By following the steps outlined in this guide, you can easily merge two files based on matching columns, resulting in a clean, organized dataset. Don't hesitate to refine the script to suit your specific needs or seek additional resources to expand your PowerShell skills.

With practice, tasks like this will become second nature, enhancing your proficiency in data management.