15.00 - DATE-to-UDT Conversion - Teradata Database

Teradata Database SQL Functions, Operators, Expressions, and Predicates

Product
Teradata Database
Release Number
15.00
Content Type
Programming Reference
Publication ID
B035-1145-015K
Language
English (United States)
Last Update
2018-09-24

DATE-to-UDT Conversion

Purpose

Converts DATE data to UDT data.

CAST Syntax

where:

 

Syntax element …

Specifies …

date_expression

a DATE expression to be cast to a UDT.

UDT_data_definition

the UDT type to which date_expression is to be converted.

ANSI Compliance

This is ANSI SQL:2011 compliant.

As an extension to ANSI, CAST permits the use of data attribute phrases such as FORMAT.

Usage Notes

Explicit DATE-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. For more information on CREATE CAST, see SQL Data Definition Language.

Implicit DATE-to-UDT Conversion

Performing an implicit data type conversion requires that an appropriate cast definition (see “Usage Notes”) exists that specifies the AS ASSIGNMENT clause.

Teradata Database performs implicit DATE-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 book, unless the DisableUDTImplCastForSysFuncOp field of the DBS Control Record is set to TRUE
  • If no DATE-to-UDT implicit cast definition exists, Teradata Database looks for other cast definitions that can substitute:

     

    IF the following combination of implicit cast definitions exists …

    THEN Teradata Database …

    Numeric-to-UDT

    Character1-to-UDT

     

    X

    uses the Numeric-to-UDT implicit cast definition.

    If multiple Numeric-to-UDT implicit cast definitions exist, then Teradata Database returns an SQL error.

     

    X

    uses the Character-to-UDT implicit cast definition.

    If multiple Character-to-UDT implicit cast definitions exist, then Teradata Database returns an SQL error.

    X

    X

    reports an error.


    1
    a non-CLOB character type

    Substitutions are valid because Teradata Database can implicitly cast a DATE type to the substitute data type, and then use the implicit cast definition to cast from the substitute data type to the UDT.

    Related Topics

    For details on data types and data attributes, see SQL Data Types and Literals.