Part 2: Step‑by‑Step Tutorial – Merging Google Sheets and Notion Data

Keeping your Google Sheets and Notion databases aligned can be tricky — especially when you already have some records on both sides. In this tutorial, you’ll learn how to merge existing data and set up Addsync.io to prevent duplicates in future syncs.

We’ll go through every step — from adding a connection to enabling merge settings — so you can safely sync Notion and Google Sheets.

📊 Before We Start

Here’s what our data looks like before merging:

Google Sheets (Before Merge)

Notion Database (Before Merge)

Before Syncing | Notiongossamer-year-ed0 on Notion

🧠 What We’re Doing

We’ll connect one Notion database (or table block) and one Google Sheet, then configure Addsync.io to merge records using a unique field — usually an ID, Email, or Project Name.

If both sides share the same value for that unique field, the record will be combined instead of duplicated. If no match is found, Addsync.io will create a new record based on your sync direction.

⚙️ Step-by-Step Setup

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Step 1 — From the Home Page, Click on “Add a Connection”

This is where we’ll create a new sync setup.

Action: From your Addsync Sheet Add on dashboard, click “Add a Connection.”

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Step 2 — Choose Notion Source

Addsync will ask which type of Notion source you want to use. Select the correct option depending on your setup:

• Notion Database → for a full database connection

• Notion Table Block → for a page table block connection

For this tutorial we going to choose Notion Database.

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Step 3 — Select a Google Sheet

Choose the Google Sheet you want to sync with Notion, then click Next.

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Step 4 — Select a Notion Database

Select the specific Notion database you want to connect with Google Sheets, then click Next again. This step will open the mapping dialog.

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Step 5 — Map Columns and Set Flow Direction

Tell Addsync which columns from Google Sheets should connect to which properties in Notion.

Google Sheets Column	Notion Property	Direction	Description
ID	ID	<->	Two-way, used for merging
Name	Name	->	From Sheets to Notion
Status	Status	<-	From Notion to Sheets

Direction Options:

• → (Sheet to Notion): Data from Google Sheets updates Notion

• ← (Notion to Sheet): Data from Notion updates Google Sheets

• ↔ (Two‑way): Data syncs both ways — whichever side updated last will overwrite the older one

You must map the column you’re using for merging, such as ID, to the same property in Notion.

After mapping, click Next.

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Step 6 — Enable Merge and Configure Matching

From the Settings page, click the toggle to enable merge before running the first sync.

Action Steps:

1. Toggle “Enable merge for next sync.”

2. Under “Match records by”, select the unique field you decided earlier — e.g., ID = ID.

3. Below that, you’ll see “Should Override” —

   • This checkbox controls whether Addsync should rewrite values depending on the sync direction.

   • Leave this enabled if you want changes from the latest update to override existing data. For this example sync setup, we’re going to enable it because Google Sheets doesn’t have the correct status values and Notion doesn’t have the correct Name values. The data will be overwritten according to the configured flow direction.

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Step 7 — Click “Done” to Merge and Create Sync Connection

Click Done to finish setup. Addsync.io will automatically begin merging records while creating the new sync connection.

You can view the merge results directly in the Logs tab to confirm which records were updated or newly created.

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✅ After Merging

Google Sheets (After Merge)

Notion Database (After Merge)

After Syncing | Notiongossamer-year-ed0 on Notion

Now your Notion database and Google Sheet are in sync — with no duplicates. Records with matching unique IDs were merged, and new rows or pages were created only when needed.

💡 Tips for Best Results

• Always test on a duplicate Sheet and Notion database before syncing real data.

• Use a unique field (ID, Email, etc.) for reliable merging.

• If duplicate records already exist before syncing, manually delete them first; merge cannot fix pre-existing duplicates.

🎯 Summary

✨ You’re done! Your Google Sheets and Notion data are now synchronized and duplicate-free.