PROPERTY expressions return properties (name-value pairs). They are typically used to provide data to other expressions. The PROPERTY NVL expression evaluates its sub-expressions and returns the properties from the first sub-expression that has a non-empty result.

This is useful if there are several different properties that a record may or may not have, but only one of them should be used in an expression. For example, a record may have a property for a home address or for a business address. PROPERTY NVL expression evaluates each possibility and returns the first address it locates.

Note that a sub-expression that returns empty strings is returning values (empty values). For example, a record may not have a value for the “Color” property; however, if the FILTER_EMPTY_PROPS attribute of the RECORD_ADAPTER is not set to true, an identity expression referencing the property "Color” still has a return value (that is, the property name “Color” with an empty value).

An NVL expression may therefore return properties with empty values; it skips only properties that do not exist. There are no EXPRNODE elements to configure PROPERTY NVL.

See the EXPRESSION element for DTD and attribute information.

<EXPRESSION TYPE="PROPERTY" NAME="NVL">
   <EXPRESSION TYPE="PROPERTY" NAME="IDENTITY">
      <EXPRNODE NAME="PROP_NAME" VALUE="address_home"/>
   </EXPRESSION>
   <EXPRESSION TYPE="PROPERTY" NAME="IDENTITY">
      <EXPRNODE NAME="PROP_NAME" VALUE="address_work"/>
   </EXPRESSION>
</EXPRESSION>