First
DataWindow expression function
Description
Reports the value in the first row in the specified column.
Syntax
|
1 |
First ( column { FOR range { DISTINCT { expresn {, expres2 {, ... } } } } } ) |
|
Argument |
Description |
|---|---|
|
column |
The column for which you want the value of the first |
|
FOR range (optional) |
The data that will be included when the value in the |
|
DISTINCT (optional) |
Causes First to consider only the distinct values in |
|
expresn (optional) |
One or more expressions that you want to evaluate to |
Return value
The datatype of the column. Returns the value in the first row of
column. If you specify range, First returns the value of the first row in
column in range.
Usage
If you specify range, First determines the value of the first row in
column in range. If you specify DISTINCT, First returns the first distinct
value in column, or if you specify expresn, the first distinct value in
column where the value of expresn is distinct.
For most presentation styles, values for range are:
-
ALL — (Default) The value in the first of all rows in
column. -
GROUP n — The value in the first of rows in column in the
specified group. Specify the keyword GROUP followed by the group
number: for example, GROUP 1. -
PAGE — The value in the first of the rows in column on a
page.
For Crosstabs, specify CROSSTAB for range to indicate the first of
all rows in column in the crosstab.
For Graphs specify GRAPH and for OLE objects specify OBJECT for
range, to indicate the value in the first row in column in the range
specified for the Rows option.
For graphs and OLE objects, you do not select the range when you
call the function. The range has already been determined by the Rows
setting on the Data property page (the Range property), and the
aggregation function uses that range. Settings for Rows include the
following:
-
For the Graph or OLE presentation style, Rows is always
All. -
For Graph controls, Rows can be All, Page, or Group.
-
For OLE controls, Rows can be All, Current Row, Page, or Group.
The available choices depend on the layer the control occupies.
Not in validation rules or filter expressions
You cannot use this or other aggregate functions in validation
rules or filter expressions.
Using an aggregate function cancels the effect of setting Retrieve
Rows As Needed in the painter. To do the aggregation, a DataWindow
object always retrieves all rows.
Examples
This expression returns the first value in column 3 on the
page:
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First(#3 for page) |
This expression returns the first distinct value in the column named
dept_id in group 2:
|
1 |
First(dept_id for group 2 DISTINCT) |
This expression returns the first value in the column named dept_id
in group 2:
|
1 |
First(dept_id for group 2) |
See also