COUNT_IF conditional counting

Concepts covered: sqlCountIf

Basic COUNT_IF COUNT_IF Syntax Calculating Percentages Conditional counts become even more powerful when converted to percentages. This reveals patterns that raw counts might hide. South has the highest completion rate (76.6%) while East has the lowest (70.8%). Raw counts alone wouldn't reveal this because South has fewer total orders. Multiple Conditions This counts only positive reviews (4+ stars) from verified purchases, giving you a more trustworthy quality metric. COUNT_IF Patterns COUNT_IF vs WHERE Before reading on, predict which approach lets you count multiple statuses in one query: See It In Action Only rows where status = 'completed' are counted toward the result. The pending and cancelled rows are skipped entirely.

About This Interactive Section

This section is part of the Aggregating: Advanced lesson on DataDriven, a free data engineering interview prep platform. Each section includes explanations, worked examples, and hands-on code challenges that execute in real time. SQL queries run against a live PostgreSQL database. Python runs in a sandboxed Docker container. Data modeling problems validate against interactive schema canvases. All content is framed around what data engineering interviewers actually test at companies like Meta, Google, Amazon, Netflix, Stripe, and Databricks.

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