15.10 - UDT_name - Teradata Database

Teradata Database SQL Data Definition Language Syntax and Examples

prodname
Teradata Database
vrm_release
15.10
created_date
December 2015
category
Programming Reference
featnum
B035-1144-151K

Name of the UDT for which information about casts is requested.

If you do not specify SOURCE or TARGET, both are reported.

SYSUDTLIB
The containing database for UDT_name.
SOURCE
Reports all cast operations that have the specified data type as their source data type.
TARGET
Reports all cast operations that have the specified data type as their target data type.

Example: Source Castings Only

The following example reports the source castings for the UDT named euro:

     HELP CAST SYSUDTLIB.euro SOURCE;
Source    Target         Cast Routine         As Assignment
---------------------------------------------------------------------
euro      DECIMAL(10,2)  System                   YES
euro      us_dollar      EurotoUS                 NO

Example: Target Castings Only

The following example reports the target castings for the UDT named euro:

     HELP CAST SYSUDTLIB.euro TARGET;
Source         Target         Cast Routine           As Assignment
----------------------------------------------------------------------
DECIMAL(10,2)  euro           System                     YES
us_dollar      euro           UstoEuro                   YES

Example: All Castings for a UDT That Has Multiple Casting Pairs

The following example shows the output of HELP CAST euro with no options:

     HELP CAST euro;
Source         Target         Cast Routine           As Assignment
----------------------------------------------------------------------
euro           DECIMAL(10,2)  System                     YES
DECIMAL(10,2)  euro           System                     YES
us_dollar      euro           UstoEuro                   YES
euro           us_dollar      EurotoUS                   NO

Note the following things about this report:

  • Because this UDT has two casting pairs (euro:DECIMAL and euro:us_dollar ), there are four rows in the report.
  • The euro:DECIMAL casting pair was system-generated (its cast routine in both cases is named System), while the euro:us_dollar casting pair was user-defined.
  • There is no implicit casting for the euro:us_dollar cast because it was not defined with the AS ASSIGNMENT option.

Example: All Castings For A UDT That Has A Single Casting Pair

The following example reports both the source and target castings for the UDT named address:

     HELP CAST address;
Source       Target           Cast Routine           As Assignment
----------------------------------------------------------------------
address      VARCHAR(80)      address_2_char             YES
VARCHAR(80)  address          char_2_address             YES

Note the following things about this report:

  • The castings from address to VARCHAR(80) and from VARCHAR(80) to address are complementary to one another.
  • Both casting routines are user-defined, because neither is named System.
  • This UDT has only one casting pair defined for it, neither of which is named System, which suggests that it is probably a structured type.

    Castings for structured types are not system-generated, while the system generates default casts for distinct types. Because it is also possible to drop the system-generated casts for a distinct UDT and replace them with user-defined casts, the inference that the casting reported in this example is for a structured UDT cannot be made with certainty. See CREATE CAST and REPLACE CAST.