FIRSTDATE() in Power BI DAX – Description & Example

🔍 What it does:

FIRSTDATE() returns the first (earliest) date in the current filter context from a column of dates.

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🧮 Syntax:

FIRSTDATE(<dates>)

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✅ Example:

First Sale Date = 
FIRSTDATE(Sales[Date])

This returns the earliest date where data exists based on the current filters (e.g., per region, product, month, etc.).

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🧠 Used with CALCULATE:

Example: Get sales on the first date of the context:

Sales on First Date = 
CALCULATE(
    SUM(Sales[Sales]),
    FIRSTDATE('DateTable'[Date])
)

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📊 Example Scenario:

If your visual shows data for March 2025, this returns 2025-03-01.

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