Datetime Expressions

A datetime expression yields a value of a datetime data type. A datetime expression has the following syntax.

datetime_value_expr AT LOCAL |

TIME ZONE { ' [ + | - ] hh:mm' | DBTIMEZONE | 'time_zone_name' | expr }

A datetime_value_expr can be a datetime value or a compound expression that yields a datetime value. Datetimes and intervals can be combined according to the rules defined in Table: Datetime Fields and Values. 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 the time zone files under oracore/zoneinfo. The server always uses the large time zone file corresponding to the version number recorded in sys.props$.

  
  

• 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.