What’s the Right Way to Join GA4 Events and CRM Orders in BigQuery?

Why join GA4 and CRM?

GA4 tells you what users did. CRM shows who actually paid. If you only look at one side, ROI analysis is incomplete. Connecting them gives you a single version of the truth.

Why is it tricky?

Joins fail for many reasons:

• Transaction IDs might be missing or inconsistent
• Timestamps don’t always align
• Events and orders follow different logic

Without careful alignment, you end up with broken attribution.

How do you make it reliable?

• Use a consistent join key like transaction_id or user_id
• Normalize formats before joining (cast IDs to string)
• Check the match rate and reconcile mismatches

This step validates whether your tracking setup is trustworthy.

What’s the outcome?

With clean joins, you can:

• Attribute revenue back to channels
• Align finance and marketing data
• Make ROI discussions based on facts, not assumptions

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