Data Validation Rules

Summary

Defining explicit rules a dataset should satisfy (dates in a valid range, no negative prices, foreign keys that actually exist) and checking new data against them automatically.

• 1Write 5 validation rules for a dataset you're working with (e.g. 'age between 0 and 120').
• 2Practice writing a query or script that flags rows violating each rule.
• 3Learn to build this into a repeatable check, not a one-time manual review.