ESQL field references

An ESQL field reference is a sequence of period-separated values that identify a specific field (which might be a structure) within a message tree or a database table. The path from the root of the information to the specific field is traced using the parent/child relationships.

A field reference is used in ESQL statements to identify the field that is to be referenced, updated, or created within the message or database table. For example, you might use the following identifier as a message field reference:

Body.Invoice.Payment

You can use an ESQL variable of type REFERENCE to set up a dynamic pointer to contain a field reference. This might be useful to create a fixed reference to a commonly-referenced point within a message, for example the start of a particular structure that contains repeating fields.

A field reference can also include namespace identification. If you refer to messages in the XMLNS and MRM message domains that include namespace support, you must include the namespace identifier when you refer to these fields.

For convenience, you can define a namespace constant using the DECLARE NAMESPACE construct and use this in place of the full namespace identifier in all applicable field references.

A field reference that identifies a well-defined location in a message tree is known as a Correlation name.

Related concepts
Message flows
Correlation names
Mappings

Related tasks
Developing message flow applications
Developing ESQL

Related reference
Built-in nodes
ESQL