16.10 - UDT Types - Teradata Database

Teradata Database SQL Fundamentals

Teradata Database
Release Number
June 2017
English (United States)
Last Update

Teradata Database supports distinct and structured UDTs.

UDT Type Description Example
Distinct A UDT that is based on a single predefined data type, such as INTEGER or VARCHAR. A distinct UDT named euro that is based on a DECIMAL(8,2) data type can store monetary data.
Structured A UDT that is a collection of one or more fields called attributes, each of which is defined as a predefined data type or other UDT (which allows nesting). A structured UDT named circle can consist of x-coordinate, y-coordinate, and radius attributes.

Distinct and structured UDTs can define methods that operate on the UDT. For example, a distinct UDT named euro can define a method that converts the value to a US dollar amount. Similarly, a structured UDT named circle can define a method that computes the area of the circle using the radius attribute.

Teradata Database also supports a form of structured UDT called dynamic UDT. Instead of using a CREATE TYPE statement to define the UDT, like you use to define a distinct or structured type, you use the NEW VARIANT_TYPE expression to construct an instance of a dynamic UDT and define the attributes of the UDT at run time.

Unlike distinct and structured UDTs, which can appear almost anywhere that you can specify predefined types, you can only specify a dynamic UDT as the data type of (up to eight) input parameters to external UDFs. The benefit of dynamic UDTs is that they significantly increase the number of input arguments that you can pass in to external UDFs.