RAQL Extensions for Dataset Schemas
Two types are available in the <variable> statement in EMML for use solely in RAQL queries:
schema is the type to use variables that declare a schema for a dataset used in
RAQL. Schemas may be defined directly in a mashup or they can be defines as global
MashZone NextGen attributes for use in several mashups.
variable:schema-type-variable-name is the type to use for variables that contain datasets used in
RAQL when a schema for that dataset has been declared in the mashup or is defined in a
MashZone NextGen global attribute. The
schema-type-variable-name is the name of an existing variable with
type="schema" that contains or references the schema for this dataset.
Variables that declare a schema provide metadata for a dataset including datatype information for columns, path information to the elements that should be treated as dataset rows and other options for datasets in the CSV format. For information about the schema syntax for datasets and examples of schemas, see
Providing Dataset Path and Datatype Information in a Schema.