SQL Data Quality Checks

Find null keys, duplicates, invalid amounts, and broken relationships.

-- 01. Find duplicate keysSELECT order_id, COUNT(*)FROM ordersGROUP BY order_idHAVING COUNT(*) > 1;

Preview uses illustrative sample content.

What’s inside

• Five read-only quality checks
• A SQLite sample dataset with intentional issues
• Expected results and adaptation notes

Make it yours

1. Extract the ZIP and read README.md. Use a disposable SQLite database to load sample-data.sql.
2. Run quality-checks.sql and compare the results with expected-results.md.
3. For your own data, change the table names, columns and rules. Run only the SELECT checks against your source; the sample setup creates demonstration tables.