External UDFs allow you to write your own functions in the C, C++, or Java programming language, install them on the database, and then use them like standard SQL functions.
You can also install external UDF objects or packages from third-party vendors.
Teradata supports three types of external UDFs.
| UDF Type | Description |
|---|---|
| Aggregate | Aggregate functions produce summary results. They differ from scalar functions in that they take grouped sets of relational data, make a pass over each group, and return one result for the group. Some examples of standard SQL aggregate functions are AVG, SUM, MAX, and MIN. |
| Scalar | Scalar functions take input parameters and return a single value result. Examples of standard SQL scalar functions are CHARACTER_LENGTH, POSITION, and TRIM. |
| Table | A table function is invoked in the FROM clause of a SELECT statement and returns a table to the statement. |