Techniques for accessing data

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:
```
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:
```
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:

**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.”