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Task 7:  Display aggregate information

One of the benefits of grouping data is that you can add summary information at the beginning or end of each group. Summary information is also known as aggregate information. In this procedure, add the following aggregate information to the report:

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Display the number of customers in each group

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In the palette, under Quick Tools, drag an aggregation element and drop it in the second cell in the group footer row. Elements that are in the group footer appear at the end of every group.
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GRP_TOTAL_CUSTOMERS
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In Aggregate On, select Group and credit_group. This value indicates that the COUNT function returns the number of rows in each credit limit group.
Figure 8-10 shows the complete definition for the aggregation element.

Figure 8-12 Aggregation Builder displaying values for getting the count of customers in each credit limit group

Figure 8-10  Aggregation Builder displaying values for getting the count of customers in each credit limit group
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Choose OK. In the report design, shown in Figure 8-11, the aggregation element displays the sigma symbol followed by the column binding name.
[GRP_TOTAL_CUSTOMER]

Figure 8-13 Report design displaying the aggregation element

Figure 8-11  Report design displaying the aggregation element
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Preview the report. The report displays the number of customers at the end of each group. Figure 8-12 shows the number of customers, 37, for the first credit limit group.

Figure 8-14 Report preview showing a count for each group

Figure 8-12  Report preview showing a count for each group
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Customers:
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Customers: <VALUE-OF>row["GRP_TOTAL_CUSTOMERS"]</VALUE-OF>
In a text element, the <VALUE-OF> tag supports the display of dynamic data. The expression, row["GRP_TOTAL_CUSTOMERS"], is a reference to the column binding you created to return the number of customers in each credit limit group.

Figure 8-15 Text specified for the text element

Figure 8-13  Text specified for the text element
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Scroll to the bottom of the first credit limit group. The report should look like the one shown in Figure 8-14. The group footer displays the following information:
Customers: 37      37

Figure 8-16 Report preview showing the text displayed by the text element

Figure 8-14  Report preview showing the text displayed by the text element
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Delete the aggregation element from the second cell in the group footer row to remove the second total, which is now redundant.

Display the total number of customers in the report

In the previous procedure, you added aggregate data by inserting the aggregation element from the palette. This time, you add aggregate data by creating a column binding through the table’s Binding page.

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In Property Editor, choose the Binding tab. The Binding page, as shown in Figure 8-15, displays all the column bindings used by elements in the table.

Figure 8-17 Binding page displaying the column bindings

Figure 8-15  Column bindings displayed
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TOTAL_CUSTOMERS
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In Aggregate On, select Table. This value indicates that the COUNT function returns the number of rows in the table. Figure 8-16 shows the complete definition for the aggregation element.

Figure 8-18 Aggregation Builder displaying values for getting the count of customers in the table

Figure 8-16  Aggregation Builder displaying values for getting the count of customers in the table
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Choose OK. The new column binding, TOTAL_CUSTOMERS, is available for use by any element in the table.
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Right-click the guide cell on the left of the first row, Table - Header, then choose InsertRowAbove. A new table header row appears above the row that displays the column headings. The new row appears in color because it inherits the properties of the row below it.
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CUSTOMER_TOTAL
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  "Number of customers: " +
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In the lower pane of the expression builder, select Available Column Bindings, select Table, then double-click TOTAL_CUSTOMERS, the column binding you created to get the number of customers in the table. The expression, row["TOTAL_CUSTOMERS"] appears after the text you typed in the text area, as shown in Figure 8-17.

Figure 8-19 The expression builder displaying the expression that refers to the TOTAL_CUSTOMERS column binding

Figure 8-17  The expression builder displaying the expression that refers to the TOTAL_CUSTOMERS column binding
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Figure 8-20 Column binding defined

Figure 8-18  Column binding defined
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Figure 8-21 Report design showing a total count for customers

Figure 8-19  Report design showing a total count for customers
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Preview the report. The report displays the number of customers at the beginning of the table, as shown in Figure 8-20. The text is centered within the column. You re-format this text later.

Figure 8-22 Report preview showing a total number of customers

Figure 8-20  Report preview showing a total number of customers

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