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# ETL: ISODatetimeToString

> Format an ISO datetime string using a custom date format pattern. Use ISODATETIMETOSTRING for converting dates to display formats in ETL jobs.

## Description

Formats a datetime string using a custom format.

## Syntax

`ISODatetimeToString(datetime_string, format_string)`

## Arguments

*datetime\_string* - string expression in ISO 8601 format.

*format\_string* - output datetime format pattern string. For formatting information, see [http://joda-time.sourceforge.net/apidocs/org/joda/time/format/DateTimeFormat.html](http://joda-time.sourceforge.net/apidocs/org/joda/time/format/DateTimeFormat.html).

## Examples

` ISODatetimeToString('2013-10-17T00:00:00.000Z','MM-dd-yy')` returns 10-17-13

## Return value datatype

string

## Notes

Returns null if ISODatetimeString is not a valid ISO 8601 datetime.

## Impact of null value

If ISODatetimeString parameter is null, returns null.

If formatString is null or bad, an exception will be raised.