Merging Datasets in Jupyter | Dataford Interview Questions

In a Jupyter notebook, use pandas to merge datasets and draw conclusions from the result

Asked in the technical round 2 stage. Write a PostgreSQL query equivalent using securities and daily_prices for February 2025.

Output

One row per active equity, including equities without February observations.
Return security_id, ticker, asset_name, observed_days, avg_close, latest_close, and coverage_status.
Ignore NULL closing prices when calculating observations and averages. Order by ticker ascending.

securities

Column	Type	Description
security_idPK	INT	Unique security identifier
ticker	VARCHAR(10)	Market ticker symbol
asset_name	VARCHAR(100)	Security name
asset_type	VARCHAR(40)	Security classification
is_active	BOOLEAN	Whether the security is currently active

daily_prices

Column	Type	Description
price_idPK	INT	Unique price observation identifier
security_id	INT	Referenced security identifier
price_date	DATE	Date of the price observation
close_price	NUMERIC(14,4)	Closing market price

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