N/query Module
Query.joinFrom()
Method Description: Creates an explicit directional join relationship from another component to this component (an inverse join). This method sets the Component.source property on the returned query.Component object. Use the method query.create(options) to create your initial query definition (query.Query). The initial query definition uses one query type. For available query types, see query.Type. After you create the initial query definition, use this method to create your first join as an explicit directional join from another component to this component. This method is a shortcut for the chained Query.root and Component.joinFrom(options): Query.root.joinFrom(options). The Query.root property references the root component, which is a query.Component object. The N/query module supports the same record types that are supported by the SuiteAnalytics Workbook interface. For more information, see Available Record Types.
Returns: query.Component
Supported Script Types: Client and server scripts For more information, see SuiteScript 2.0 Script Types.
Governance: None
Module: N/query Module
Parent Object: query.Query
Sibling Object Members: Query Object Members
Since: 2018.2
Search NetSuite - https://system.netsuite.com/app/help/helpcenter.nl?search=Query.joinFrom(options)

// Code Example 1

// Add additional code

//...

var myEmployeeQuery = query.create({

    type: query.Type.EMPLOYEE

});



var myTransactionJoin = myEmployeeQuery.joinFrom({

    fieldId: 'entity',

    source: 'transaction'

});



myEmployeeQuery.columns = [

    myEmployeeQuery.createColumn({

        fieldId: 'entityid'

    }),

    myTransactionJoin.createColumn({

        fieldId: 'entity'

    }),

    myTransactionJoin.createColumn({

        fieldId: 'daysoverduesearch'

    })

];

//...

// Add additional code



//SOURCE: https://system.netsuite.com/app/help/helpcenter.nl?fid=section_1530819218.html