[Cardagant]

Попробуйте вот так:

    Query query = new Query();
    QueryBuildDataSource qbds,qbdt;
    ;

    query.queryType(QueryType::Union);
    qbds = query.addDataSource(tablenum(VendInvoiceJour));
    qbdt = query.addDataSource(tablenum(CustInvoiceJour));
    
    qbds.fields().clearFieldList();
    qbdt.fields().clearFieldList();
    
    qbds.addSelectionField(fieldnum(VendInvoiceJour, InvoiceID));
    qbds.addSelectionField(fieldnum(VendInvoiceJour, InvoiceDate));
    qbdt.addSelectionField(fieldnum(CustInvoiceJour, InvoiceID));
    qbdt.addSelectionField(fieldnum(CustInvoiceJour, InvoiceDate));