BOL о возможных значения @@cursor_rows
"m - The cursor is populated asynchronously. The value returned (-m) is the number of rows currently in the keyset.

-1 - The cursor is dynamic. Because dynamic cursors reflect all changes, the number of rows that qualify for the cursor is constantly changing. It can never be definitely stated that all qualified rows have been retrieved .

0 - No cursors have been opened, no rows qualified for the last opened cursor, or the last-opened cursor is closed or deallocated.

n - The cursor is fully populated. The value returned (n) is the total number of rows in the cursor.
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