NAME

DateTime::Format::Oracle - Parse and format Oracle dates and timestamps

SYNOPSIS

  use DateTime::Format::Oracle;

  $ENV{'NLS_DATE_FORMAT'} = 'YYYY-MM-DD HH24:MI:SS';
  my $dt = DateTime::Format::Oracle->parse_datetime('2003-01-16 23:12:01');
  my $string = DateTime::Format::Oracle->format_datetime($dt);

DESCRIPTION

This module may be used to convert Oracle date and timestamp values into DateTime objects. It also can take a DateTime object and produce a date string matching the NLS_DATE_FORMAT.

Oracle has flexible date formatting via its NLS_DATE_FORMAT session variable. Date values will be returned from Oracle according to the current value of that variable. Date values going into Oracle must also match the current setting of NLS_DATE_FORMAT.

Timestamp values will match either the NLS_TIMESTAMP_FORMAT or NLS_TIMESTAMP_TZ_FORMAT session variables.

This module keeps track of these Oracle session variable values by examining environment variables of the same name. Each time one of Oracle's formatting session variables is updated, the %ENV hash must also be updated.

METHODS

This class offers the following methods.

nls_date_format

This method is used to determine the current value of Oracle's NLS_DATE_FORMAT. It currently just reads the value from
```
  $ENV{'NLS_DATE_FORMAT'}
```
or if that is not set, from the package variable $nls_date_format, which has a default value of YYYY-MM-DD HH24:MI:SS. This is a good default to have, but is not Oracle's default. Dates will fail to parse if Oracle's NLS_DATE_FORMAT and the value from this method are not the same.

If you want to use the default from this module, you can do something like this after you connect to Oracle:
```
  $dbh->do(
      "alter session set nls_date_format = '" .
      DateTime::Format::Oracle->nls_date_format .
      "'"
  );
```
nls_timestamp_format

This method is used to determine the current value of Oracle's NLS_TIMESTAMP_FORMAT. It currently just reads the value from
```
  $ENV{'NLS_TIMESTAMP_FORMAT'}
```
or if that is not set, from the package variable $nls_timestamp_format, which has a default value of YYYY-MM-DD HH24:MI:SS. This is a good default to have, but is not Oracle's default. Dates will fail to parse if Oracle's NLS_TIMESTAMP_FORMAT and the value from this method are not the same.

If you want to use the default from this module, you can do something like this after you connect to Oracle:
```
  $dbh->do(
      "alter session set nls_timestamp_format = '" .
      DateTime::Format::Oracle->nls_timestamp_format .
      "'"
  );
```
nls_timestamp_tz_format

This method is used to determine the current value of Oracle's NLS_TIMESTAMP_TZ_FORMAT. It currently just reads the value from
```
  $ENV{'NLS_TIMESTAMP_TZ_FORMAT'}
```
or if that is not set, from the package variable $nls_timestamp_tz_format, which has a default value of YYYY-MM-DD HH24:MI:SS TZHTZM. This is a good default to have, but is not Oracle's default. Dates will fail to parse if Oracle's NLS_TIMESTAMP_TZ_FORMAT and the value from this method are not the same.

If you want to use the default from this module, you can do something like this after you connect to Oracle:
```
  $dbh->do(
      "alter session set nls_timestamp_tz_format = '" .
      DateTime::Format::Oracle->nls_timestamp_tz_format .
      "'"
  );
```
parse_datetime

Given a string containing a date and/or time representation matching NLS_DATE_FORMAT, this method will return a new DateTime object.

If given an improperly formatted string, this method may die.
parse_date

Alias to parse_datetime. Oracle's date datatype also holds time information.
parse_timestamp

Given a string containing a date and/or time representation matching NLS_TIMESTAMP_FORMAT, this method will return a new DateTime object.

If given an improperly formatted string, this method may die.
parse_timestamptz =item * parse_timestamp_with_time_zone

Given a string containing a date and/or time representation matching NLS_TIMESTAMP_TZ_FORMAT, this method will return a new DateTime object.

If given an improperly formatted string, this method may die.
current_date_parser

The current DateTime::Format::Builder generated parsing method used by parse_datetime and parse_date.
current_timestamp_parser

The current DateTime::Format::Builder generated parsing method used by parse_timestamp.
current_timestamptz_parser

The current DateTime::Format::Builder generated parsing method used by parse_timestamptz.
format_datetime

Given a DateTime object, this method returns a string matching the current value of NLS_DATE_FORMAT.

It is important to keep the value of $ENV{'NLS_DATE_FORMAT'} the same as the value of the Oracle session variable NLS_DATE_FORMAT.

To determine the current value of Oracle's NLS_DATE_FORMAT:
```
  select NLS_DATE_FORMAT from NLS_SESSION_PARAMETERS
```
To reset Oracle's NLS_DATE_FORMAT:
```
  alter session set NLS_DATE_FORMAT='YYYY-MM-DD HH24:MI:SS'
```
It is generally a good idea to set NLS_DATE_FORMAT to an unambiguos value, with four-digit year, and hour, minute, and second.
format_date

Alias to format_datetime.
format_timestamp

Given a DateTime object, this method returns a string matching the current value of NLS_TIMESTAMP_FORMAT.

It is important to keep the value of $ENV{'NLS_TIMESTAMP_FORMAT'} the same as the value of the Oracle session variable NLS_TIMESTAMP_FORMAT.

To determine the current value of Oracle's NLS_TIMESTAMP_FORMAT:
```
  select NLS_TIMESTAMP_FORMAT from NLS_SESSION_PARAMETERS
```
To reset Oracle's NLS_TIMESTAMP_FORMAT:
```
  alter session set NLS_TIMESTAMP_FORMAT='YYYY-MM-DD HH24:MI:SS'
```
It is generally a good idea to set NLS_TIMESTAMP_FORMAT to an unambiguos value, with four-digit year, and hour, minute, and second.
format_timestamptz =item * format_timestamp_with_time_zone

Given a DateTime object, this method returns a string matching the current value of NLS_TIMESTAMP_TZ_FORMAT.

It is important to keep the value of $ENV{'NLS_TIMESTAMP_TZ_FORMAT'} the same as the value of the Oracle session variable NLS_TIMESTAMP_TZ_FORMAT.

To determine the current value of Oracle's NLS_TIMESTAMP_TZ_FORMAT:
```
  select NLS_TIMESTAMP_TZ_FORMAT from NLS_SESSION_PARAMETERS
```
To reset Oracle's NLS_TIMESTAMP_TZ_FORMAT:
```
  alter session set NLS_TIMESTAMP_TZ_FORMAT='YYYY-MM-DD HH24:MI:SS TZHTZM'
```
It is generally a good idea to set NLS_TIMESTAMP_TZ_FORMAT to an unambiguos value, with four-digit year, and hour, minute, and second.
current_date_format

The current generated method used by format_datetime, format_date, and current_date_parser to keep track of the strptime translation of NLS_DATE_FORMAT.
current_timestamp_format

The current generated method used by format_timestamp, format_timestamp_with_time_zone, and current_timestamp_parser to keep track of the strptime translation of NLS_TIMESTAMP_FORMAT.
current_timestamptz_format

The current generated method used by format_timestamptz, format_timestamp_with_time_zone, and current_timestamp_parser to keep track of the strptime translation of NLS_TIMESTAMP_FORMAT.
oracle_to_posix

Given an NLS_DATE_FORMAT, NLS_TIMESTAMP_FORMAT, or NLS_TIMESTAMP_TZ_FORMAT value, this method returns a DateTime-compatible strptime format value.

Translation is currently handled by Convert::NLS_DATE_FORMAT.

LIMITATIONS

Oracle is more flexible with the case of names, such as the month, whereas DateTime generally returns names in ucfirst format.

  MONTH -> FEBRUARY
  Month -> February
  month -> february

All translate to:

  %B    -> February

TIME ZONES

Oracle returns all dates and timestamps in a time zone similar to the DateTime floating time zone, except for 'timestamp with time zone' columns.

INTERVAL ELEMENTS

I have not implemented parse_duration, format_duration, parse_interval, nor format_interval, and have no plans to do so.

If you need these features, unit tests, method implementations, and pointers to documentation are all welcome.

SUPPORT

Support for this module is provided via the datetime@perl.org email list. See http://lists.perl.org/ for more details.

TODO

Possibly read an environment variable to determine a time zone to use instead of 'floating'.

Test and document creating an instance via new.

AUTHOR

Nathan Gray, <kolibrie@cpan.org>

ACKNOWLEDGEMENTS

I might have put this module off for another couple years without the lure of Jifty, Catalyst, and DBIx::Class pulling at me.

Thanks to Dan Horne for his RFC draft of this module.

COPYRIGHT & LICENSE

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.4 or, at your option, any later version of Perl 5 you may have available.

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