Functional Training for Field Validation

Learn to build the validation types you'll use every day, Mandatory, Filter, Length, Related Field, Related No. of Records, and Regular Expression.
Understand Warning versus Error properly, control exactly when a rule triggers with Conditions, set up starting state with Init Values, and understand what a table relation actually is and where it's used across validation types.
Learn to use Check Table to find existing records that don't meet a validation rule.