borland Packages Class Hierarchy dx.dataset Package
com.borland.dx.dataset.CalcType
Variables
The CalcType
interface defines the types of calculations that a Column
may involve: no calculations, a calculated value, an aggregate value, or a lookup. Use the constants defined in this class with the calcType
property of a Column
component.
When you set the calcType
property to AGGREGATE
, you must also set the associated aggregation properties in the AggDescriptor
object. These properties indicate the Columm
to perform the aggregation on, subtotal grouping, and the type of aggregator operation (sum, count, minimum value or maximum value). You access the AggDescriptor
object through the agg
property in the JBuilder Inspector.
When working with calculated fields, set the Column
component's calcType
property to
CALC
, then set the code for the calculation in the Column
component's calcFields
event handler. The calcFields
event handler method is called for calculated columns whenever a field value is set and whenever a row is posted.
For more information on using calculated columns, see "Using calculated columns" in the Database Application Developer's Guide.
When working with lookup fields, set the Column
component's calcType
property to
LOOKUP
and its pickList
property to a PickListDescriptor
which describes the lookup relationship. In particular, the PickListDescriptor
property of LookupDisplayColumn
must be set to the Column
to display the lookup values.
For examples of applications that use calculated values, see the following projects in the specified directories of your JBuilder installation:
public static final int AGGREGATE = 2Constant used to designate a calculated field that summarizes across multiple rows. To work with an aggregation calculation, set the
agg
property of the Column
to the AggDescriptor
object that contains the properties associated with the aggregation.
public static final int CALC = 1Constant used to designate a basic calculated field that is updated by the
calcFields
event of a Column
when rows are changed or added.
public static final int LOOKUP = 3Constant used to designate that this column gets its value from a
Column
in another DataSet
. The Column.PickList
property must be set with the PickList.LookupDisplayColumn
set to a non-null value for the lookup to work.
public static final int NO_CALC = 0Constant used to designate that a calculation is not used for this
Column
.