Using DataWindow expression functions
In the DataWindow painter, you can use DataWindow expression
functions in expressions for computed fields, filters, validation rules,
and graphed data, with some exceptions.
The dialog boxes in which you define expressions include a list box
that lists the available functions and their arguments. The dialog boxes
make it easy to insert a function into the expression.
For information about expressions, see DataWindow Operators and
Expressions
Return values for functions and
expressions
DataWindow expression functions can return the following
datatypes:
| Double |
| Decimal |
| String |
| DateTime |
| Time |
Within an expression, a function can return other datatypes (such as
boolean, date, or integer), but the final value of an expression is
converted to one of these datatypes.
Restrictions for aggregate
functions
An aggregate function is a function (such as Avg, Max, StDev, and
Sum) that operates on a range of values in a column. When you use an
aggregate function, some restrictions apply. You cannot use an aggregate
function:
-
In a filter
-
In a validation rule
-
As an argument for another aggregate function
When you use aggregate functions, they cancel the effect of setting
Retrieve Rows As Needed. To do the aggregation, the DataWindow
object always retrieves all rows.
User-defined functions in
PowerBuilder
You can include user-defined functions in DataWindow expressions.
The datatype of the function’s return value can be any of the following:
double, decimal, string, boolean, date, DateTime, or time. The function
must be defined as a global function so that it is available to the
DataWindow object. However, a global function argument of datatype boolean
cannot be provided by a DataWindow expression because it does not map to
any of the datatypes listed in Return values for functions and
expressions.
Built-in DataWindow expression functions cannot be overridden. For
example, if you create a global function called Today, it is used instead
of the PowerScript system function Today, but it is not used instead of
the DataWindow expression function Today.
Formatting for the locally correct display of
numbers
No matter what country you are creating objects and developing an
application in, you must use U.S. number notation in numbers or number
masks in display formats, edit masks, and DataWindow expressions. This
means that when you specify a number or number mask, use a comma as the
thousands delimiter and period for the decimal place.
Numbers display appropriately in whatever countries you deploy
applications in. At runtime, the locally correct symbols for numbers
display (because the international Control Panel settings are used) when
numbers are interpreted. For example, in countries where comma represents
the decimal place and period represents thousands, users see numbers in
those formats at runtime.
For information about the locally correct display of dates and day
names, see String and DayName.