OFFSET

Article
12/13/2022
3 minutes to read

Returns a single row that is positioned either before or after the current row within the same table, by a given offset. If the current row cannot be deduced to a single row, multiple rows may be returned.

Syntax

OFFSET ( <delta>[, <relation>][, <orderBy>][, <blanks>][, <partitionBy>] )

Parameters

Term	Definition
delta	The number of rows before (negative value) or after (positive value) the current row from which to obtain the data. It can be any DAX expression that returns a scalar value.
relation	(Optional) A table expression from which the output row is returned. If specified, all columns in <orderBy> and <partitionBy> must come from it. If omitted: - <orderBy> must be explicitly specified. - All <orderBy> and <partitionBy> columns must be fully qualified and come from a single table. - Defaults to ALLSELECTED() of all columns in <orderBy> and <partitionBy>.
orderBy	(Optional) An ORDERBY() clause containing the columns that define how each partition is sorted. If omitted: - <relation> must be explicitly specified. - Defaults to ordering by every column in <relation> that is not already specified in <partitionBy>.
blanks	(Optional) An enumeration that defines how to handle blank values when sorting. This parameter is reserved for future use. Currently, the only supported value is KEEP (default), where the behavior for numerical/date values is blank values are ordered between zero and negative values. The behavior for strings is blank values are ordered before all strings, including empty strings.
partitionBy	(Optional) A PARTITIONBY() clause containing the columns that define how <relation> is partitioned. If omitted, <relation> is treated as a single partition.

Return value

One or more rows from <relation>.

Remarks

Each <orderBy> and <partitionBy> column must have a corresponding outer value to help define the current row on which to operate, with the following behavior:

If there is exactly one corresponding outer column, its value is used.
If there is no corresponding outer column, then:
- OFFSET will first determine all <orderBy> and <partitionBy> columns that have no corresponding outer column.
- For every combination of existing values for these columns in OFFSET’s parent context, OFFSET is evaluated and a row is returned.
- OFFSET’s final output is a union of these rows.
If there is more than one corresponding outer column, an error is returned.

If the columns specified within <orderBy> and <partitionBy> can't uniquely identify every row in <relation>, then:

OFFSET will try to find the least number of additional columns required to uniquely identify every row.
If such columns can be found, OFFSET will automatically append these new columns to <orderBy>, and each partition is sorted using this new set of OrderBy columns.
If such columns cannot be found, an error is returned.

An empty table is returned if:

The corresponding outer value of an OrderBy or PartitionBy column does not exist within <relation>.
The <delta> value causes a shift to a row that does not exist within the partition.

If OFFSET is used within a calculated column defined on the same table as <relation>, and <orderBy> is omitted, an error is returned.

Example 1

The following DAX query:

DEFINE
VAR vRelation = SUMMARIZECOLUMNS ( 
                    DimProductCategory[EnglishProductCategoryName], 
                    DimDate[CalendarYear], 
                    "CurrentYearSales", SUM(FactInternetSales[SalesAmount]) 
                  )
EVALUATE
ADDCOLUMNS (
    vRelation, 
    "PreviousYearSales", 
    SELECTCOLUMNS(
        OFFSET ( 
                -1, 
                vRelation, 
                ORDERBY([CalendarYear]), 
                PARTITIONBY([EnglishProductCategoryName])
        ),
        [Current Sales]
    )
)

Returns a table that summarizes the total sales for each product category and calendar year, as well as the total sales for that category in the previous year.

Example 2