Create Validation function for UNIQUE constraint over multiple fields

We are currently only able to validate that a single field is unique in its table. However, there are use-cases in which a pair or more of attributes should be unique inside the table. In SQL this can be expressed using a constraint such as:

ALTER TABLE recipes ADD CONSTRAINT recipes_unique_name_in_group UNIQUE (group_id, name);

It would be good if we had a function similar to validateIsUnique that validates this constraint.

Naming suggestions:

• validateAreUnique
• validateIsUniqueComposite
• validateAreUniqueFields
• validateIsUniqueSet