OpenOverlayCursor Method
Description
Opens a new cursor containing specified fields for all items in an overlay.
Syntax
Visual Basic |
---|
Public Function OpenOverlayCursor( _ ByVal cursor As String, _ ByVal pos As Long, _ ByVal fields As String, _ ByVal bForwardOnly As Long _ ) As Integer |
Parameters
- cursor
- The named cursor to be created with the specified fields for all items in an overlay. Any existing cursor with this name will be overwritten.
- pos
- The position in the overlays list of the overlay from which to fill the cursor.
- fields
- The list of fields to be included in the cursor. Field names should be as they appear in the expression box within SIS and should be TAB-separated.
- bForwardOnly
-
True
you can pass forward only through the records (a Forward-Only cursor is slightly more efficient) False
you can navigate forwards and backwards through the records at will.
Remarks
OpenOverlayCursor inserts a row into the cursor for every item in the whole overlay.
In the case of dynamically connected cursor-based datasets, e.g. a Spatial Table in Oracle, the overlay is deemed to be the whole Spatial Table and so OpenOverlayCursor will create a cursor for the whole Spatial Table which might be undesirable.
When a cursor is opened the current reading position is at the start of the cursor.
A cursor can be opened onto the schema columns by leaving the fields parameter empty.
Available: GEO D OD OM SISpy
Group:
Example
VB.net:
sis.OpenOverlayCursor ( "MyCursor", 1, "_area#" & vbTab & "UPRN$" & vbTab & "BDRMS&", FALSE )
Python:
cursor_columns = ["_area#", "UPRN$", "BDRMS&"]
sis.OpenOverlayCursor ( "MyCursor", 0, "\t".join(cursor_columns), False)
Note: vbTab, used in VB.net, is not valid in Python and is replaced with "\t", this is the same for C#.
This example creates a cursor called MyCursor which will contain three columns - the system property _area# and two user-defined properties.
The cursor will be populated from items on overlay number 1 and will contain a row for every item in that overlay. It is possible to navigate forwards and backwards through this cursor to visit or revisit any row.