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How to add a computed field to a data set

You must define a data set before you can add a computed field. For information about defining a data set, see the appropriate section .

  1. In Edit Data Set, choose Computed Columns.
  2. You can reach Edit Data Set by right-clicking an existing data set and choosing Edit from the context menu.
    Edit Data Set--Computed Columns appears.

  3. Under Column Name, select the first empty row and type the name of the computed field.
  4. Under Expression, specify the expression to calculate the desired value. You can either type the expression or use Expression Builder to construct the expression. To use Expression Builder, perform the following steps:
    1. Choose the ellipsis (...) button.
    2. Expression Builder appears.
    3. In Available objects, expand the nodes to see operators and other objects you can use in an expression.
    4. In the top pane, type an expression. You also can also double-click an item in Available objects to add it to the expression at the insertion point.
    5. Choose OK.
    6. Edit Data Set--Computed Columns appears. It displays the computed field and expression you created.

  5. To see all the columns specified in the data set, choose Output Columns.
  6. Choose Preview Results to make sure the computed field returns the correct data. Preview Results also shows the query results, as shown in the following illustration.
  7. Choose OK.
  8. BIRT Report Designer saves the data set.

 


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