Question

This is my first time truly working with composite keys. I have a record that consists of three foreign key columns. The combination of these three keys must be unique. If a duplicate record is inserted, a constrain error should be thrown just as if it were a unique, single-field, primary key.

This is for Teradata database.

Answer 1

You can enforce this via a unique secondary index on the table.

CREATE UNIQUE INDEX {optional name} ({column1}, {column2}, ... column{64}) ON {database}.{table};

You could also consider adding a UNIQUE CONSTRAINT on the table as well if the inclusion of the INDEX would not benefit as an alternative access method.

Teradata also supports the use of Primary Key constraints if you are planning to enforce RI in your environment.