SQL Vendor Performance Query | Dataford Interview Questions

Write a SQL query to analyze operational performance by vendor at Scale, including throughput, average turnaround time, and error rate over time. Use the provided vendor and job data. Treat completed and error jobs as processed, calculate turnaround time for completed jobs, and exclude in-progress jobs from throughput and error-rate calculations.

Output

One row per vendor and month with processed jobs.
Columns: vendor_name, period_month, throughput, average_turnaround_minutes, and error_rate_pct.
Sort by vendor_name, then period_month ascending.

Schema

vendors

Column	Type	Description
vendor_idPK	INT	Unique vendor identifier
vendor_name	VARCHAR(100)	Scale vendor name

jobs

Column	Type	Description
job_idPK	INT	Unique job identifier
vendor_id	INT	Vendor assigned to the job
started_at	TIMESTAMP	Job processing start time
completed_at	TIMESTAMP	Job completion or terminal status time
status	VARCHAR(20)	Job status

Your question is SQL Vendor Performance Query. Start with the requirements and the two tables in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem