When you assign a default time zone to a user, each time that user logs onto the database, their session uses the assigned time zone offset.
The valid range for a time zone offset specified as ± ‘quotestring’ is from -12:59 to +14.00.
If you set the default time zone offset for a user by specifying a non-GMT time zone string, the database can change the time zone automatically whenever there is a change in Daylight Saving Time. Only those time zone strings that are not defined in terms of GMT enable automatic adjustments for Daylight Saving Time. The GMT time zones are designed to be used for locations or time zones that do not follow Daylight Saving Time.
The following table documents the time zone options and their definitions.
|LOCAL||The value for the local time zone displacement defined as the system default for this user.
Note that this is a persistent setting. If the system-defined default time zone should change, the value defined for the user remains at the value defined for it when she was created.
To change the value, you must submit a MODIFY USER request (see MODIFY USER).
|NULL||No default time zone displacement is defined for the user.|
|± ‘quotestring’||An optionally signed text string that sets a non-system-default interval offset for converting the user default time zone displacement.
The format is hh:mm.
|‘time_zone_string’||Sets the value of the default time zone for the user to the displacement specified by ‘time_zone_string’.
If you specify an explicit non-GMT time zone string, it is passed to a system-defined UDF named GetTimeZoneDisplacement that interprets the string and determines the appropriate time zone displacement for the session (see Teradata Vantage™ - SQL Date and Time Functions and Expressions, B035-1211for information about the GetTimeZoneDisplacement UDF).
Time zone strings that are expressed in terms of GMT do not enable automatic adjustments for Daylight Savings Time. Regions that do not follow Daylight Savings Time are only represented by GMT values.
The following table documents the time zone strings supported by Vantage.
|Time Zone Strings|
See Teradata Vantage™ - SQL Date and Time Functions and Expressions, B035-1211 for the definition of the GetTimeZoneDisplacement UDF that converts time zone values when Daylight Saving Time changes.
See Teradata Vantage™ - Database Utilities, B035-1102 for information about the DBS Control flags SystemTimeZoneHour, SystemTimeZoneMinute, and TimeDateWZControl and their control of the automatic conversion of Daylight Saving Time to standard time and back.
See Teradata Vantage™ - Database Utilities, B035-1102 for information about the tdlocaledef utility and how it is used to specify rules for time zone strings.