CURRENT_DATE
Purpose
Returns the current date.
Syntax
where:
|
Syntax element … |
Specifies … |
|
AT LOCAL |
that the value returned is constructed from the session time and session time zone if the DBS Control flag TimeDateWZControl is enabled. If TimeDateWZControl is disabled, the value returned is constructed from the time value local to the Teradata Database server and the session time zone. |
|
AT [TIME ZONE] expression |
that the time zone displacement defined by expression is used. The data type of expression should be INTERVAL HOUR(2) TO MINUTE or it must be a data type that can be implicitly converted to INTERVAL HOUR(2) TO MINUTE. For details, see “AT LOCAL and AT TIME ZONE Time Zone Specifiers” on page 827. |
|
AT [TIME ZONE] time_zone_string |
that time_zone_string is used to determine the time zone displacement. For details, see “AT LOCAL and AT TIME ZONE Time Zone Specifiers” on page 827. |
ANSI Compliance
CURRENT_DATE and the AT clause are ANSI SQL:2011 compliant.
As an extension to ANSI, you can specify an AT clause after the CURRENT_DATE function, and you can specify the time zone displacement using additional expressions besides an INTERVAL expression.
Usage Notes
CURRENT_DATE returns the current date at the time when the request started. If CURRENT_DATE is invoked more than once during the request, the same date is returned. The date returned does not change during the duration of the request.
If you specify CURRENT_DATE without the AT clause or CURRENT_DATE AT LOCAL, then the value returned depends on the setting of the DBS Control flag TimeDateWZControl as follows:
For more information, see “DBS Control (dbscontrol)” in Utilities: Volume 1 (A-K).
CURRENT_DATE returns a value that is adjusted to account for the start and end of daylight saving time (DST) only in the following cases:
For more information about time zone strings, see “AT LOCAL and AT TIME ZONE Time Zone Specifiers” on page 827.
Result Type and Attributes
The result data type, format, and title for CURRENT_DATE are:
|
Data Type |
Format |
Title |
|
DATE |
Default format for the DATE data type when the Dateform mode is set to IntegerDate. For more information on the default formats, see “Data Type Formats and Format Phrases” in SQL Data Types and Literals. |
Date |
To convert CURRENT_DATE, use Teradata explicit conversion syntax or ANSI CAST syntax. For an example that uses Teradata explicit conversion syntax to change the default output format, see “Example 3: Changing the Default Output Format” on page 358.
CURRENT_DATE versus DATE
CURRENT_DATE provides similar functionality to the Teradata function DATE using ANSI-compliant syntax. For information on the Teradata DATE function, see “DATE” on page 365.
Example
This example assumes that the default format for DATE values is 'yy/mm/dd'. Consider the following statements:
SET TIME ZONE INTERVAL '01:00' HOUR TO MINUTE;
SELECT CURRENT_DATE AT TIME ZONE INTERVAL -'08:00' HOUR TO MINUTE;
SELECT CURRENT_DATE AT INTERVAL -'08:00' HOUR TO MINUTE;
SELECT CURRENT_DATE AT TIME ZONE INTERVAL -'08' HOUR;
SELECT CURRENT_DATE AT INTERVAL -'08' HOUR;
SELECT CURRENT_DATE AT TIME ZONE '-08:00';
SELECT CURRENT_DATE AT '-08:00';
SELECT CURRENT_DATE AT TIME ZONE '-8';
SELECT CURRENT_DATE AT '-8';
SELECT CURRENT_DATE AT TIME ZONE -8;
SELECT CURRENT_DATE AT -8;
SELECT CURRENT_DATE AT -8.0;
The above SELECT statements return the current date based on the time zone displacement, INTERVAL -'08:00' HOUR TO MINUTE. If the current timestamp at UTC is TIMESTAMP '2008-06-01 06:30:00.000000+00:00', these SELECT statements would return '08/05/31' as the date.
If the SELECT statement was specified without an AT clause or with an AT LOCAL clause,
and the DBS Control flag TimeDateWZControl is enabled, the statement would return
'08/06/01' as the current date based on the current session time and time zone displacement,
INTERVAL '01:00' HOUR TO MINUTE. For example:
SELECT CURRENT_DATE;
SELECT CURRENT_DATE AT LOCAL;
The date returned is not adjusted to account for the start or end of daylight saving time.
Example
This example assumes that the default format for DATE values is 'yy/mm/dd'. Consider the following statements:
SET TIME ZONE INTERVAL '01:00' HOUR TO MINUTE;
SELECT CURRENT_DATE AT INTERVAL '09:00' HOUR TO MINUTE;
The above SELECT statement returns the current date based on the time zone displacement, INTERVAL '09:00' HOUR TO MINUTE. If the current timestamp at UTC is TIMESTAMP '2008-06-01 19:30:00.000000+00:00', the SELECT statement would return '08/06/02' as the date.
If the SELECT statement was specified without an AT clause or with an AT LOCAL clause,
and the DBS Control flag TimeDateWZControl is enabled, the statement would return
'08/06/01' as the current date based on the current session time and time zone displacement,
INTERVAL '01:00' HOUR TO MINUTE.
The date returned is not adjusted to account for the start or end of daylight saving time.
Example
This example assumes that the default format for DATE values is 'yy/mm/dd'. Consider the following statements:
SET TIME ZONE INTERVAL '10:00' HOUR TO MINUTE;
SELECT CURRENT_DATE AT '05:45';
SELECT CURRENT_DATE AT 5.75;
The above SELECT statements return the current date based on the time zone displacement, INTERVAL '05:45' HOUR TO MINUTE. If the current timestamp at UTC is TIMESTAMP '2008-06-01 17:30:00.000000+00:00', the SELECT statements would return '08/06/01' as the date.
If the SELECT statement was specified without an AT clause or with an AT LOCAL clause,
and the DBS Control flag TimeDateWZControl is enabled, the statement would return
'08/06/02' as the current date based on the current session time and time zone displacement,
INTERVAL '10:00' HOUR TO MINUTE.
The date returned is not adjusted to account for the start or end of daylight saving time.
Example
The following queries return the current date at the time zone displacement based on the time zone string, 'America Pacific'. Teradata Database determines the time zone displacement based on the time zone string and the CURRENT_TIMESTAMP AT '00:00' (that is, at UTC). The date returned is automatically adjusted to account for the start and end of daylight saving time.
SELECT CURRENT_DATE AT TIME ZONE 'America Pacific';
SELECT CURRENT_DATE AT 'America Pacific';
Example : Changing the Default Output Format
To change the default output format of the CURRENT_DATE result, use Teradata explicit conversion syntax and specify the FORMAT phrase. For example, the following statement requests the current date and specifies a format that is different from the default:
SELECT CURRENT_DATE (FORMAT 'MMMBDD,BYYYY');
The result is similar to:
Date
------------
May 31, 2007
For more information on Teradata explicit conversion syntax, see “Teradata Conversion Syntax in Explicit Data Type Conversions” on page 593. For more information on default data type formats and the FORMAT phrase, see “Data Type Formats and Format Phrases” in SQL Data Types and Literals.