Oracle® Database SQL Reference 10g Release 2 (10.2) Part Number B14200-02 |
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A datetime expression yields a value of one of the datetime datatypes.
datetime_expression::=
A datetime_value_expr
can be a datetime column or a compound expression that yields a datetime value. Datetimes and intervals can be combined according to the rules defined in Table 2-5. The three combinations that yield datetime values are valid in a datetime expression.
If you specify AT
LOCAL
, Oracle uses the current session time zone.
The settings for AT
TIME
ZONE
are interpreted as follows:
The string '(+|-)HH:MM'
specifies a time zone as an offset from UTC.
DBTIMEZONE
: Oracle uses the database time zone established (explicitly or by default) during database creation.
SESSIONTIMEZONE
: Oracle uses the session time zone established by default or in the most recent ALTER
SESSION
statement.
time_zone_name
: Oracle returns the datetime_value_expr
in the time zone indicated by time_zone_name
. For a listing of valid time zone names, query the V$TIMEZONE_NAMES
dynamic performance view.
Note:
Timezone region names are needed by the daylight savings feature. The region names are stored in two time zone files. The default time zone file is a small file containing only the most common time zones to maximize performance. If your time zone is not in the default file, then you will not have daylight savings support until you provide a path to the complete (larger) file by way of theORA_TZFILE
environment variable.See Also:
Oracle Database Administrator's Guide for more information about setting the ORA_TZFILE
environment variable
Oracle Database Globalization Support Guide. for a complete listing of the timezone region names in both files
Oracle Database Reference for information on the dynamic performance views
expr
: If expr
returns a character string with a valid time zone format, Oracle returns the input in that time zone. Otherwise, Oracle returns an error.
Example The following example converts the datetime value of one time zone to another time zone:
SELECT FROM_TZ(CAST(TO_DATE('1999-12-01 11:00:00', 'YYYY-MM-DD HH:MI:SS') AS TIMESTAMP), 'America/New_York') AT TIME ZONE 'America/Los_Angeles' "West Coast Time" FROM DUAL; West Coast Time ------------------------------------------------ 01-DEC-99 08.00.00.000000 AM AMERICA/LOS_ANGELES