MarkLogic 9 Product Documentationop:join-left-outer
op:join-left-outer( $leftPlan as map:map, $rightPlan as map:map, [$keys as map:map*], [$condition as map:map?] ) as map:map
Summary
This method yields one output row set with the rows from an inner join as well as rows from the left row set.
The join performs natural joins between columns with the same identifiers. To prevent inadvertent natural joins, specify a different qualifier for the left or right columns or use different column names for the left and right columns.
| Parameters | |
|---|---|
| $leftPlan | The row set from the left view. |
| $rightPlan | The row set from the right view. |
| $keys | The equijoin from one or more calls to the op:on function. |
| $condition | A boolean expression that filters the join output rows. |
Example
xquery version "1.0-ml";
import module namespace op="http://marklogic.com/optic"
at "/MarkLogic/optic.xqy";
let $employees := op:from-view("main", "employees")
let $expenses := op:from-view("main", "expenses")
let $totalexpenses := op:col("totalexpenses")
return $employees
=> op:join-left-outer($expenses, op:on(
op:view-col("employees", "EmployeeID"),
op:view-col("expenses", "EmployeeID")))
=> op:group-by(op:view-col("employees", "EmployeeID"),
("FirstName", "LastName",
op:view-col("expenses", "Category"),
op:sum($totalexpenses,
op:view-col("expenses", "Amount"))))
=> op:order-by(op:view-col("employees", "EmployeeID"))
=> op:result()