External Types - FastExport

The “from‑sql routine” and the “to‑sql routine” create a mapping between a UDT and a pre‑defined type. This pre‑defined type is called the external type of a UDT. A client application only deals with the external type; it does not deal with UDT value directly.

External Type Example

For example, if the following conditions exist:

UDT named FULLNAME exists

The external type associated with FULLNAME is VARCHAR(46)

Then, during an retrieve of FULLNAME values, the Teradata Database server converts the values from FULLNAME values to VARCHAR(46) values by invoking the “from‑sql routine” associated with the FULLNAME UDT.

Note: The client must expect to receive the data in the same format as it receives VARCHAR(46) values.

Similarly, when values are provided by the client for insert into a FULLNAME UDT, the client must provide values in the same way it would provide values for a VARCHAR(46) field. The Teradata Database server will convert the values from VARCHAR(46) to FULLNAME values using the “to‑sql routine” associated with the FULLNAME UDT.