How to Clean Excel Data Before Running SQL Queries

Raw spreadsheet data is messy. Before you can use it in a database query, you need to clean it. Here's how to handle the common problems.

Problem 1: Duplicates

Your list has the same ID multiple times:

Running this in an IN clause wastes processing time. Enable "Remove Duplicates" to get:

Problem 2: Whitespace

Copy-paste from spreadsheets often adds hidden spaces:

These won't match your database records. "Trim Whitespace" fixes it:

Problem 3: Leading Zeros

Part numbers and ZIP codes often have leading zeros:

Excel sometimes drops them, or your database expects them. Two options:

Trim Leading Zeros: Removes them for integer comparison

Fill Leading Zeros: Pads to a consistent length (e.g., 5 digits)

Problem 4: Trailing Punctuation

Exports sometimes include stray punctuation:

Enable "Trim Punctuation" to clean it up:

Putting It Together

Before:

After (with all cleaning enabled):

IN ('SKU-001', 'SKU-002', 'SKU-003')

Three duplicates removed, whitespace trimmed, punctuation stripped, proper SQL formatting applied.

When to Keep Duplicates

Sometimes duplicates matter:

• Counting occurrences in test data
• Verifying data integrity
• Reproducing specific scenarios

Toggle off "Remove Duplicates" when you need the original count.