The FIELDVALUE field function returns the scalar value of a given field.
FIELDVALUE returns the scalar value of the field identified by source_field_reference. If it identifies a non-existent field, NULL is returned.
<Data> <Qty Unit="Gallons">1234</Qty> </Data>The ESQL statement
SET OutputRoot.XML.Data.Quantity = FIELDVALUE(InputRoot.XML.Data.Qty);gives the result:
<Data><Quantity>1234</Quantity></Data>whereas this ESQL statement (without the FIELDVALUE function):
SET OutputRoot.XML.Data.Quantity = InputRoot.XML.Data.Qty;causes a tree copy, with the result:
<Data><Quantity Unit="Gallons">1234</Quantity></Data>because the field Qty is not a leaf field.