The TO_DATE function converts a formatted TEXT or NTEXT expression to a DATETIME value.
The text expression that contains a date to be converted. The expression can have the TEXT or NTEXT data type. A conversion from NTEXT can result in an incorrect result when the NTEXT value cannot be interpreted as a date.
A text expression that identifies a datetime format template. This template specifies how the conversion from text to DATETIME should be performed. For information about datetime format templates, see Table 9-4, "Datetime Format Elements".
An OLAP option (such as NLS_DATE_LANGUAGE) and its new setting, which temporarily overrides the setting currently in effect for the session. Typically, this option identifies the language of text-exp when it is different from the session language. See Example 8-140, "Specifying a Default Language and a Date Format".
Do not specify an option that sets other options. For example, do not set NLS_LANGUAGE or NLS_TERRITORY; set NLS_DATE_LANGUAGE instead. While TO_DATE saves and restores the current setting of the specified option so that it has a new value only for the duration of the statement, TO_DATE cannot save and restore any side effects of changing that option. For example, NLS_TERRITORY controls the value of NLS_DATE_FORMAT, NLS_NUMERIC_CHARACTERS, NLS_CURRENCY, NLS_CALENDAR, and other options. When you change the value of NLS_TERRITORY in a call to TO_DATE, all of these options are reset to their territory-appropriate default values twice: once when NLS_TERRITORY is set to its new value for the duration of the TO_DATE statement, and again when the saved value of NLS_TERRITORY is restored.
Capital letters in words, abbreviation, or Roman numerals in a format element produce corresponding capitalization in the return value. For example, the format element DAY produces MONDAY, Day produces Monday, and day produces monday.
When TO_DATE cannot construct a value with a valid DATE value using fmt, it returns an error. For example, when an alphanumeric character appears in text-exp where fmt indicates a punctuation character, then an error results.
Example 8-139 Converting Text Values to DATE Values
The following statement converts January 15, 2002, 11:00 A.M. to the default date format of 15JAN02, and stores that value in a DATE variable named bonusdate.
bonusdate = TO_DATE('January 15, 2002, 11:00 A.M.', -
'Month dd, YYYY, HH:MI A.M.')
Example 8-140 Specifying a Default Language and a Date Format
The following statements set the default language to Spanish and specify a new date format. The NLS_DATE_LANGUAGE option, when used in the TO_DATE function, allows the American month name to be translated.
NLS_DATE_FORMAT = 'Day: Month dd, yyyy HH:MI:SS am'
NLS_DATE_LANGUAGE = 'spanish'
SHOW TO_DATE('November 15, 2001', 'Month dd, yyyy', -
NLS_DATE_LANGUAGE 'american')
The date is translated from American to Spanish and displayed in the new date format.
Jueves : Noviembre 15, 2001 12:00:00 AM