MySQL 8.0 C API Developer Guide
MYSQL_ROW_OFFSET mysql_row_tell(MYSQL_RES *result)
          Returns the current position of the row cursor for the last
          mysql_fetch_row(). This value
          can be used as an argument to
          mysql_row_seek().
        
          Use mysql_row_tell() only
          after mysql_store_result(),
          not after mysql_use_result().