LINQ Queries for Data Access | Dataford Interview Questions

Write LINQ queries for a .NET application and explain how you would use them in database access at Balyasny Asset Management.

For this exercise, provide the PostgreSQL equivalent that a LINQ provider should generate. Include active portfolios, current active positions, aggregated gross exposure, and an exposure classification.

Output

One row per active portfolio, including portfolios with no qualifying positions.
Columns: portfolio_id, portfolio_name, active_position_count, gross_exposure, and exposure_band.
Sort by gross_exposure descending, then portfolio_id ascending.

Schema

portfolios

Column	Type	Description
portfolio_idPK	INT	Unique portfolio identifier
portfolio_name	VARCHAR(100)	Portfolio display name
manager_name	VARCHAR(100)	Portfolio manager name
is_active	BOOLEAN	Whether the portfolio is active

positions

Column	Type	Description
position_idPK	INT	Unique position identifier
portfolio_id	INT	Referenced portfolio
instrument_id	INT	Referenced instrument
quantity	NUMERIC(18,4)	Signed position quantity
as_of_date	DATE	Position valuation date

instruments

Column	Type	Description
instrument_idPK	INT	Unique instrument identifier
symbol	VARCHAR(20)	Instrument symbol
sector	VARCHAR(60)	Instrument sector
last_price	NUMERIC(18,4)	Latest available instrument price
is_active	BOOLEAN	Whether the instrument is active

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