DataSet

Parent of simple data set and joint data set.

Description

See Also

computedColumns

User-defined columns in the result set.

Description

A computed column is a user-defined column produced as an expression of other columns within the data set�s primary result set. It is not of the columns retrieved directly from the underlying data provider.

See Also

ComputedColumn structure

columnHints

Defines the report-related data attributes of the result set�s columns.

Description

In BIRT, a result set column can be defined with an alias.  Aliases are useful in cases where a column name is awkward, or is used by multiple columns in a result set.

BIRT reports provide a rich viewing experience. The user can search the report, extract data to a file, export data to an OLAP system, and more. Such operations work on the actual data set�s result set instead of on the presentation of the data. Column hints let the report developer customize the search and data extract experience.

The column hint element provides a number of "hints" about result set columns. The hints override BIRT defaults for how columns are handled during viewing. Hints can be provided for both retrieved and computed columns.

Column hints are keyed to the data set�s primary result set using names. The user must understand how to keep the hints in sync with the data set when either the data set definition, or underlying data source, changes.

BIRT uses the column hints in the following cases:

In each case, BIRT checks whether the data set provides the requested column. If so, it continues processing the report.  If not, it issues a fatal runtime error.

See Also

ColumnHint structure

filter

An optional set of filters to apply to the result set before any other data transforms. 

Description

An optional set of filters that apply to the data set�s primary result set.  A data set�s filter is applied to each row of the retrieved result set before any other data transforms.  The filter expression should thus not contain any aggregation functions.  It usually references at least one column from a data row, and may also reference a report parameter or other scripting variable.

See Also

Filter Criteria structure

Listing filter property

ListingGroup filter property

cachedMetaData

Cached derived data attributes of a data set.

Description

Defines the cached derived data attributes of a data set. The BIRT designer uses the cached information until the user initiates refresh and reconciles with the latest derived data attributes provided by the connected data source. This property is used during report design time only; its content is maintained by the BIRT designer tool.

See Also

CachedMetaData structure