This is a feature of JBuilder Professional and Enterprise.
To display this dialog, select the agg
property in the Inspector when a Column
of a DataSet
component is selected in the structure pane.
Use the Agg
property editor to specify data aggregation properties from within the JBuilder UI Designer. Calculated aggregated columns can be used to group and/or summarize data, for example, to summarize total sales by quarter. Aggregation calculations can be specified completely through property settings and any number of columns can be included in the grouping. Four types of aggregation are supported (sum, count, min, and max) as well as a mechanism for creating custom aggregation methods.
The aggregate can be computed for the entire data set, or you can group by one or more columns in the data set and compute an aggregate value for each group. The calculated aggregated column is defined in the data set being summarized, so every row in a group will have the same value in the calculated column (the aggregated value for that group). The column is hidden by default. You can choose to show the column or show its value in another control. For more information, see Aggregating data with calculated fields in Database Application Developer's Guide. The aggDescriptor
property is used to specify columns to group, the column to aggregate, and the aggregation operation to perform. Properties specified in this dialog are stored in an instance of an AggDescriptor
object.
The list of columns in the DataSet
from which you can select when choosing columns for grouping the data. Column names displayed in Grouping Columns are excluded from this list.
Highlight a column name then select Add To Group to add a column to the grouping. When you do this, the column name disappears from this list and is added to the Grouping Columns list.
Removes the currently selected column name from the Available Columns list and adds it to the Grouping Columns list.
The columns of the DataSet
by which the aggregation should be grouped. Only non-calculated, non-aggregate column names are allowed in this list.
Removes the currently selected column name from the Grouping Columns list and displays it in the Available Columns list.
Select this if you want to perform a custom aggregation, for example, a calculation on the aggregated values could involve the sum of line items multiplied by a constant "markup" amount. Selecting this field assigns a null value to the Aggregate Column and Aggregate Operation fields (which indicates a calculated aggregate operation), and disables both fields.
To specify a custom aggregate, select this option and
CalcType.AGGREGATE
CalcAggFieldsListener
with the aggregate column's DataSet
Select the column from the DataSet
whose values are going to be summarized in the aggregation operation. This column should be added to the data set prior to setting properties in the agg
property editor. When the column is created, be sure to set its calcType
property to aggregated
, and its visible
property to Yes
.
Warning: if you set this column to a column that currently contains data, the data will be overwritten with the aggregated data.
Select the class that provides the functionality for the aggregation operation you are performing. This list displays all AggOperators
as well as user-defined ones within the same class context as the Aggregate Column value. Pre-defined aggregating operators include CountAggOperator
(for counting the number of occurrences in the group), MaxAggOperator
(for finding the maximum value in the group), MinAggOperator
(for finding the minimum value in the group), SumAggOperator
(for summing all the values in the group).