ROWNUMBER DAX Function

Returns the unique rank for the current context within the specified partition sorted by the specified order or on the axis specified.

Syntax

ROWNUMBER ( [<Relation>] [, <OrderBy>] [, <Blanks>] [, <PartitionBy>] [, <MatchBy>] [, <Reset>] )

Parameter	Attributes	Description
Relation	Optional	A table expression where the RANK is computed. If omitted, OrderBy must be explicitly specified.
OrderBy	Optional	Columns that define how each partition is sorted. If omitted, Relation must be explicitly specified.
Blanks	Optional	Defines how to handle BLANK OrderBy values. Valid values include: DEFAULT, FIRST, LAST.
PartitionBy	Optional	Columns that define how Relation is partitioned.
MatchBy	Optional	Columns that define how the current row is identified.
Reset	Optional	Specifies how the calculation restarts. Valid values are: None, LowestParent, HighestParent, or an integer.

Learn more about ROWNUMBER in the following articles:

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Contributors: Alberto Ferrari, Marco Russo