MarkLogic 10 Product Documentationop:has-group-key
op:has-group-key( $outputColumn as xs:string, $column as columnIdentifier ) as map:map
Summary
This aggregate function adds a flag to a grouped row specifying whether a column acted as a grouping key for the row.
The flag column has a value of 0 in result rows belonging to a group that has the group key and a value of 1 in other result rows. The aggregate is useful for the op:group-by-union function in cases where the grouping key is nullable and, thus, null values in the grouping key column are insufficient to distinguish rows grouped on a null value from rows that don't belong to a group with the grouping key.
| Parameters | |
|---|---|
| $outputColumn | The name to be used for the aggregated flag column. |
| $column | The column to flag as a grouping key. The column can be named with a string or a column parameter function such as op:col or constructed from an expression with op:as. |
See Also
Example
xquery version "1.0-ml";
import module namespace op="http://marklogic.com/optic"
at "/MarkLogic/optic.xqy";
op:from-view("main", "expenses")
=> op:group-by-union(
(op:group(), op:group(("Category", "Location"))),
(op:has-group-key("Category"), op:has-group-key("Location"), op:sum("TotalAmount", "Amount"))
)
=> op:order-by(("Category", "Location"))
=> op:result()