Two techniques

There are two ways to access data values in a DataWindow control:

• Methods

  SetItem and the group of GetItem methods
  access single values in specific rows and columns. For example:

  PowerBuilder

  dw_1.SetItem(1, "empname", "Phillips")

  1	dw_1.SetItem(1, "empname", "Phillips")

  PowerBuilder

  ls_name = dw_1.GetItemString(1, "empname")

  1	ls_name = dw_1.GetItemString(1, "empname")

• Expressions

  DataWindow data expressions use dot notation and can refer
  to single items, columns, blocks of data, selected data, or the
  whole DataWindow control. For example:

  PowerBuilder

  dw_1.Object.empname[1] = "Phillips"

  1	dw_1.Object.empname[1] = "Phillips"

  PowerBuilder

  dw_1.Object.Data[1,1] = "Phillips"

  1	dw_1.Object.Data[1,1] = "Phillips"

Both methods allow you to access data in any buffer and to
get original or current values.

Which technique to use

The technique you use depends on how much data you are accessing
and whether you know the names of the DataWindow columns when the
script is compiled:

Table 4-1: Which technique to use when accessing data

If you want to access	Use
A single item	Either an expression or a method. Both are equally efficient when referring to single items. Exception If you want to use a column’s name rather than its number, and the name is not known until runtime, use a method; methods allow you to name the column dynamically.
More than one item, such as: All the data in a column A block of data specified by ranges of rows and columns Data in selected rows All the data in the DataWindow	An expression. Specifying the data you want in a single statement is much more efficient than calling the methods repeatedly in a program loop.

What’s in this section

The rest of this section describes how to construct expressions
for accessing DataWindow data. The section “Syntaxes for DataWindow
data expressions “ provides reference
information on the syntaxes for data expressions.

For information on methods

For information about using methods for accessing data, see SetItem, GetItemDate, GetItemDateTime, GetItemDecimal, GetItemNumber, GetItemString, and GetItemTime in Chapter 9, “Methods for the DataWindow Control.”