Creating Alternate Key Entity Constraints (continued)
3. Select the columns to use.
4. Choose the Alternate Key constraint type. You may elect to make the Alternate Key attributes mandatory, which will be automatically validated at run time by the implicit entity-level MandatoryAttributesValidator, which loops through all mandatory constraints on the row.
If you want to check the uniqueness of the key, you must explicitly add an entity-level Unique Key validator on the Alternate Key attributes. Adding a validator is explained in the lesson titled “Validating User Input.”