Techniques for accessing data – PB Docs 2021

Techniques
for accessing data

Contents

About DataWindow data expressions

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

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2

dw_1.SetItem(1, "empname", "Phillips")
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" dw_1.Object.Data[1,1] = "Phillips"

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2

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

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.

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

GetItemTime in Methods for the DataWindow
Control

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Powerbuilder Documentation 2021