Create
method (DataWindows)
Description
Creates a DataWindow object using DataWindow source code and puts
that object in the specified DataWindow control or DataStore object. This
dynamic DataWindow object does not become a permanent part of the
application source library.
Applies to
|
DataWindow type |
Method applies to |
|---|---|
|
PowerBuilder |
DataWindow control, DataStore object |
Syntax
PowerBuilder
|
1 |
integer dwcontrol.Create ( string syntax {, string errorbuffer } ) |
|
Argument |
Description |
|---|---|
|
dwcontrol |
A reference to the DataWindow control or DataStore in |
|
syntax |
A string whose value is the DataWindow source code |
|
errorbuffer (optional) |
The name of a string that will hold any error |
Return value
In PowerBuilder, returns 1 if it succeeds and -1 if an error
occurs.
If any argument’s value is null, the method returns null.
Usage
The Create method creates a DataWindow object using the source code
in syntax. It substitutes the new DataWindow object for the DataWindow
object currently associated with dwcontrol.
DataWindow source code syntax is complex and is best produced by
copying existing DataWindows. In a PowerBuilder application, you can use
the Describe and LibraryExport methods to obtain the source code of
existing DataWindows to use as models. In the PowerBuilder development
environment, you can export the syntax of a DataWindow object in the
Library painter.
Another source of DataWindow code is the SyntaxFromSQL method, which
creates DataWindow source code based on a SQL statement. Many values in
the source code syntax correspond to properties of the DataWindow object,
which are documented in DataWindow
Object Properties.
When you examine syntax for existing DataWindow objects, you will
see that the order of the syntax can vary. Release must be the first
statement, and DataWindow should be the next statement. If you change the
order, use care; the order can affect the results.
Calling SyntaxFromSQL as the syntax argument
You can call SyntaxFromSQL directly as the value for syntax.
However, this does not give you the chance to check whether errors have
been reported in its error argument. Before you use SyntaxFromSQL in
Create, make sure the SQL syntax is valid.
Comments
To designate text in your DataWindow syntax as a comment, use either
of the standard PowerBuilder methods:
-
Use double slashes (//) to indicate that the text after the
slashes and on the same line is a comment.When you use this method, the comment can be all or part of a
line but cannot cover multiple lines; the compiler ignores everything
following the double slashes on the line. -
Begin a comment with slash asterisk (/*) and end it with
asterisk slash (*/) to indicate that all the text between the
delimiters is a comment.When you use this method, the comment can be all or part of a
line or occupy multiple lines; the compiler ignores everything between
/* and */.
For DataWindows in group
boxes
If a DataWindow object is in a group box, it is not automatically
moved to the top when you call Create, even if the BringToTop property is
set to true in the DataWindow painter. You must explicitly set the
BringToTop property to true after you call Create. For example:
|
1 2 |
dw_1.Create(ls_syntax, ls_errors) dw_1.BringToTop=true |
Examples
These statements create a new DataWindow in the control dw_new from
the DataWindow source code returned by the SyntaxFromSQL method. Errors
from SyntaxFromSQL and Create are displayed in the MultiLineEdits mle_sfs
and mle_create. After creating the DataWindow, you must call
SetTransObject for the new DataWindow object before you can retrieve
data:
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 |
string error_syntaxfromSQL, error_create string new_sql, new_syntax new_sql = 'SELECT emp_data.emp_id, ' & + 'emp_data.emp_name ' & + 'from emp_data ' & + 'WHERE emp_data.emp_salary>45000' new_syntax = SQLCA.SyntaxFromSQL(new_sql, & 'Style(Type=Form)', error_syntaxfromSQL) IF Len(error_syntaxfromSQL) > 0 THEN // Display errors mle_sfs.Text = error_syntaxfromSQL ELSE // Generate new DataWindow dw_new.Create(new_syntax, error_create) IF Len(error_create) > 0 THEN mle_create.Text = error_create END IF END IF dw_new.SetTransObject(SQLCA) dw_new.Retrieve() |
See also
SyntaxFromSQL in the section called “SyntaxFromSQL” in PowerScript Reference