result_id is a valid result id (select type queries only, and only if a "scrollable" cursor was requested when calling sesam_query()).
whence sets the global default value for the scrolling type, it specifies the scroll type to use in subsequent fetch operations on "scrollable" cursors, which can be set to the following predefined constants:
表格 1. Valid values for "whence" parameter
| Value | Constant | Meaning |
|---|---|---|
| 0 | SESAM_SEEK_NEXT | read sequentially |
| 1 | SESAM_SEEK_PRIOR | read sequentially backwards |
| 2 | SESAM_SEEK_FIRST | fetch first row (after fetch, the default is set to SESAM_SEEK_NEXT) |
| 3 | SESAM_SEEK_LAST | fetch last row (after fetch, the default is set to SESAM_SEEK_PRIOR) |
| 4 | SESAM_SEEK_ABSOLUTE | fetch absolute row number given as offset (Zero-based. After fetch, the default is set to SESAM_SEEK_ABSOLUTE, and the offset value is auto-incremented) |
| 5 | SESAM_SEEK_RELATIVE | fetch relative to current scroll position, where offset can be a positive or negative offset value (this also sets the default "offset" value for subsequent fetches). |
offset is an optional parameter which is only evaluated (and required) if whence is either SESAM_SEEK_RELATIVE or SESAM_SEEK_ABSOLUTE.