Rules for Positioning the Scrollable Cursor

There are rules that govern the position of the cursor in fetch_orientation options when you are fetching the cursor rows, where cursPos is the cursor position.

See the fetch_orientation

These terms used in rules for positioning the scrollable cursor are:

curRowsetStart – the cursor’s current position.
new_CurRowsetStart – the new current position of the cursor.
total_rows – the total number of rows in the cursor result set.
before_first – the row position before the first row of the cursor result set. This variable has a value of 0.
after_last – the row position after the last row of the cursor result set. This variable has a value of total_rows + 1.
first_row – the position at the first row of the cursor result set. This variable has value of 1.
last_row – the position at the last row of the cursor result set. This variable has the same value as total_rows.
fetchSize – the number of rows requested for each fetch operation.

Rule	Description
Fetch first	The `new_CurRowsetStart` always moves to `first_row`, regardless of the position of `CurRowsetStart` and the value of `fetchSize`.
Fetch last	If `total_rows` >= `fetchSize`, then `new_CurRowsetStart` = `total_rows` – `fetchSize` + 1. If `total_rows` < `fetchSize`, then `new_CurRowsetStart` is on `first_row`.
Fetch next	If `CurRowsetStart` is `before_first`, then `new_CurRowsetStart` is on `first_row`. Let `curPos` = (`CurRowsetStart` + `fetchSize`), `curPos` <=`total_rows`, then `new_CurRowsetStart` = `curPos` `curPos` > `total_rows`, `new_CurRowsetStart` is `after_last` If `CurRowsetStart` is `after_last` row, then `new_CurRowsetStart` remains on `after_last`.
Fetch prior	`new_CurRowsetStart` is `before_first` when one of these conditions is true: (`CurRowsetStart` >= 1) && (`CurRowsetStart` - `fetchSize` <=0) `CurRowsetStart` is `before_first` Let `curPos` = `CurRowsetStart` – `fetchSize`; iff 1 <=`curPos` <=`total_rows`, then `new_CurRowsetStart` = `curPos`. If (`CurRowsetStart` is `after_last`), let `curPos` = `total_rows` – `fetchSize` + 1 `new_CurRowsetStart` = `curPos` if `curPos` > 0 `new_CurRowsetStart` is `before_first` if `curPos` <= 0
Fetch relative	If (`CurRowsetStart` is `before_first`) && (`fetch_offset` > 0), then `new_CurRowsetStart` = `fetch_offset`. `new_CurRowsetStart` is `before_first` if one of these conditions is true: (`CurRowsetStart` is `before_first`) and (`fetch_offset` < 0) (`CurRowsetStart` is on `first_row`) and (`fetch_offset` < 0) (`CurRowsetStart` is `after_last`) and ((`CurRowsetStart` + `fetch_offset` + 1) <= 0) If (1 < `CurRowsetStart` <= `total_rows`), let `curPos` = `CurRowsetStart` + `fetch_offset`, then: `new_CurRowsetStart` is on `first_row` iff (`curPos` < 1) and `abs` (`fetch_offset`) <= `fetchSize` `new_CurRowsetStart` is before `first_row` iff (`curPos` < 1) && (`abs` (`fetch_offset`) `fetchSize`) `new_CurRowsetStart` = `curPos` iff (0 < `curPos` <=`total_rows`) `new_CurRowsetStart` is `after_last` iff `curPos` > `total_rows` If (`CurRowsetStart` is `after_last`), let `curPos` = `CurRowsetStart` + `fetch_offset` +1, then: `new_CurRowsetStart` = `curPos` iff 1 <= `curPos` <= `total_rows` `new_CurRowsetStart` is `before_first` iff `curPos` <= 0 `new_CurRowsetStart` is `after_last` iff `curPos` > `total_rows`
Fetch absolute	If `fetch_offset` = 0, `new_CurRowsetStart` is `before_first` If `fetch_offset` > `total_rows`, `new_CurRowsetStart` is `after_last` If 0 < `fetch_offset` <= `total_rows`, `new_CurRowsetStart` = `fetch_offset` If (`fetch_offset` < 0) && (`abs` (`fetch_offset`) > `total_rows`), let `abs_offset` = `abs` (`fetch_offset`) `new_CurRowsetStart` is `before_first` iff `abs_offset` > `fetchSize` `new_CurRowsetStart` is on `first_row` iff `abs_offset` <= `fetchSize` If (`fetch_offset` < 0) && (`abs` (`fetch_offset`) <= `total_rows`) `new_CurRowsetStart` = `total_rows` + `fetch_offset` + 1