This function is only available when connected to a Teradata database.
The Reset When Expression is an optional component of the ordered analytical functions (with the exception of Moving Linear Regression) and is used to specify conditional partitions within the window partitions, if any. It is displayed in parentheses to emphasize that it is just a component and not an entire function in itself, and is only available when version 13.00 or later of Teradata is in use.
To use this feature, drag a Reset When Expression element into the Partition Columns folder of an ordered analytical function, after any partitioning columns or expressions. An example of the result is given below.
A Reset When Expression may be used only if one or more Sort Expressions entries are present. Note that it is not unusual for a Reset When expression to include an ordered analytical function, but if it does, the Ordered Analytical function must not contain a Reset When expression itself.