UDT-to-INTERVAL Conversion - Teradata Database

UDT-to-INTERVAL Conversion

Purpose

Converts a UDT expression to an INTERVAL data type.

CAST Syntax

where:

Syntax element …	Specifies …
UDT_expression	an expression that results in a UDT data type. For details on expressions that can result in UDT data types, see “SQL UDF” on page 1318.
interval_data_definition	the target predefined interval type followed by optional NAMED or TITLE attribute phrases.

ANSI Compliance

This is ANSI SQL:2011 compliant.

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

Teradata Conversion Syntax

where:

Syntax element …	Specifies …
UDT_expression	an expression that results in a UDT data type. For details on expressions that can result in UDT data types, see “SQL UDF” on page 1318.
data_attribute	one of the following optional data attributes: NAMED TITLE
interval_data_type	the target predefined interval type to which UDT_expression is to be converted.

ANSI Compliance

This is a Teradata extension to the ANSI SQL:2011 standard.

Usage Notes

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 Type Conversion

Performing an implicit data type conversion requires a cast definition (see “Usage Notes”) that specifies the following:

the AS ASSIGNMENT clause

a target data type that is in the same INTERVAL family as the target of the implicit cast:

This INTERVAL data type …	Belongs to this INTERVAL family …
INTERVAL YEAR INTERVAL YEAR TO MONTH INTERVAL MONTH	Year-Month
INTERVAL DAY INTERVAL DAY TO HOUR INTERVAL DAY TO MINUTE INTERVAL DAY TO SECOND INTERVAL HOUR INTERVAL HOUR TO MINUTE INTERVAL HOUR TO SECOND INTERVAL MINUTE INTERVAL MINUTE TO SECOND INTERVAL SECOND	Day-Time

The target data type of the cast definition does not have to be an exact match to the target of the implicit type conversion.

Teradata Database performs implicit UDT-to-INTERVAL 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

Example  

Consider the following table definition, where datetime_record is a UDT:

   CREATE TABLE support

      (id INTEGER

      ,information datetime_record );

Assuming an appropriate cast definition exists for the datetime_record UDT, the following statement converts the values in the information column to INTERVAL MONTH:

   SELECT id, CAST (information AS INTERVAL MONTH) FROM support;

Related Topics

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