Implicit UDT-to-Character 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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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 UDT-to-character 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

Performing an implicit data type conversion requires that an appropriate cast definition exists that specifies the AS ASSIGNMENT clause.

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

If multiple implicit cast definitions exist for converting the UDT to different character types, Vantage 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

If no UDT-to-character implicit cast definitions exist, Vantage looks for other cast definitions that can substitute for the UDT-to-character implicit cast definition:

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

If multiple UDT-to-numeric implicit cast definitions exist, then Analytics Database returns an SQL error.
  X     Uses UDT-to-DATE implicit cast definition.
    X   Uses UDT-to-TIME implicit cast definition.
      X Uses UDT-to-TIMESTAMP implicit cast definition.
X X     Returns 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 Analytics Database can use the implicit cast definition to cast the UDT to the substitute data type, and then implicitly cast the substitute data type to a character type.