Implicit Character-to-UDT Conversion - Teradata Vantage

Teradata® VantageCloud Lake
Deployment
VantageCloud
Edition
Lake
Product
Teradata Vantage
Published
January 2023
Language
English (United States)
Last Update
2024-04-03
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Explicit character-to-UDT conversion using Teradata conversion syntax is not supported.

Data type conversions involving UDTs require appropriate cast definitions for the UDTs. To define a cast for a UDT, use the CREATE CAST statement.

Analytics Database performs implicit Character-to-UDT conversions for the following operations:
  • UPDATE
  • INSERT
  • Passing arguments to stored procedures, external stored procedures, UDFs, and UDMs
  • Specific system operators and functions identified in other sections of this document

The source character type of the cast definition does not have to be an exact match to the source character type of the implicit conversion. Analytics Database can use an implicit cast definition that specifies a CHAR, VARCHAR, or CLOB source type.

If multiple implicit cast definitions exist for converting different character types to the UDT, Analytics Database uses the implicit cast definition for the character type with the highest precedence. The following list shows the precedence of character types in order from lowest to highest precedence:
  • CHAR
  • VARCHAR
  • CLOB

For non-CLOB character types, if no Character-to-UDT implicit cast definitions exist, Analytics Database looks for other cast definitions that can substitute.

Implicit Cast Definition Combination Analytics Database Action
Numeric-to-UDT DATE-to-UDT TIME-to-UDT TIMESTAMP-to-UDT
X       Uses numeric-to-UDT implicit cast definition.

If multiple numeric-to-UDT implicit cast definitions exist, Analytics Database returns SQL error.
  X     Uses the DATE-to-UDT implicit cast definition.
    X   Uses the TIME-to-UDT implicit cast definition.
      X Uses the TIMESTAMP-to-UDT implicit cast definition.
X X     Reports error.
X   X  
X     X
  X X  
  X   X
    X X
X X X  
X X   X
X   X X
  X X X
X X X X

Substitutions are valid because Vantage can implicitly cast the non-CLOB character type to the substitute data type, and then use the implicit cast definition to cast from the substitute data type to the UDT.