Writing a Complex SQL Query | Dataford Interview Questions

Can you provide an example of a complex SQL query you wrote and explain its purpose?

Use the provided relational tables to produce a representative example. The query should summarize qualifying analyst activity and make the purpose of each major operation clear.

Output

One row per analyst and dataset with at least two query runs from 2025 onward.
Return dataset_name, analyst_name, successful_runs, total_runs, success_rate_pct, latest_success_at, and dataset_rank.
Rank analysts within each dataset by success rate, then successful runs, descending. Sort by dataset name, rank, and analyst name.

Schema

analysts

Column	Type	Description
analyst_idPK	INT	Unique analyst identifier
analyst_name	VARCHAR(100)	Analyst display name

query_runs

Column	Type	Description
run_idPK	INT	Unique query run identifier
analyst_id	INT	Analyst who initiated the run
dataset_id	INT	Dataset queried by the run
status	VARCHAR(20)	Run outcome
started_at	DATE	Run start date
runtime_seconds	INT	Elapsed runtime in seconds

datasets

Column	Type	Description
dataset_idPK	INT	Unique dataset identifier
dataset_name	VARCHAR(120)	Dataset display name
dataset_type	VARCHAR(40)	Dataset classification

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