How would you handle a dataset with thousands of duplicate records?

Handling a dataset with thousands of duplicate records in Excel requires a systematic approach to ensure data integrity while removing unnecessary duplicates. Here’s how you can manage it:

1. Identify & Remove Duplicates Using Built-in Excel Feature

If you want to remove exact duplicates:

Steps :

Select the dataset (including column headers).
Go to the Data tab → Click Remove Duplicates.
Select the columns to check for duplicates.
Click OK → Excel removes duplicate records.

* Best for: Removing complete duplicate rows.

2. Highlight Duplicates Using Conditional Formatting

If you want to review duplicates before deleting them:

Steps :

Select the dataset.
Go to Home → Conditional Formatting → Highlight Cell Rules → Duplicate Values.
Choose a formatting style and click OK.

* Best for: Visually identifying duplicates before taking action.

3. Find & Remove Duplicates Using a Helper Column

If you need custom duplicate detection, use the COUNTIF function.

Steps :

Add a helper column next to your dataset.
Use this formula to flag duplicates:
```
=COUNTIF(A:A, A2) > 1
```
- This returns TRUE for duplicates.
Filter the column for TRUE and delete duplicate rows.

* Best for: Detecting partial duplicates or applying manual checks.

4. Remove Duplicates Using Power Query (For Large Datasets)

If you’re dealing with huge datasets (thousands of records), Power Query is efficient.

Steps :

Select the dataset → Go to Data → Click Get & Transform Data → From Table/Range.
In Power Query, select columns to check for duplicates.
Go to Home → Click Remove Duplicates.
Click Close & Load to import the cleaned data.

* Best for: Large datasets with complex duplicate conditions.

5. Using Advanced Filters to Extract Unique Records

If you want to extract a unique list without deleting data:

Steps :

Select the dataset.
Go to Data → Advanced Filter.
Choose Copy to another location.
Check Unique records only and select where to copy.
Click OK.

* Best for : Keeping the original dataset untouched while working with unique values.

Best Method to Use Based on Your Needs

Method	Best For
Remove Duplicates	Quick deletion of exact duplicate rows
Conditional Formatting	Identifying duplicates visually
COUNTIF Formula	Custom duplicate detection
Power Query	Handling large datasets efficiently
Advanced Filter	Extracting unique records without deleting