oci_cancel() invalidates a cursor, freeing all associated resources and cancels the ability to read from it.
成功した場合に TRUE 、失敗した場合に FALSE を返します。
In PHP versions before 5.0.0 you must use ocicancel() instead. This name still can be used, it was left as alias of oci_cancel() for downwards compatability. This, however, is deprecated and not recommended.