上海交通大学交大密西根 联合学院·一 ◆ UM-SJTU Joint Institute University of Michigan Shanghal Jiao Tong University Sequential Characteristics One usually uses sequential files for writing and reading data that is not changed later and that is read all at once.It is the most efficient way of storing files which have variable length records. Changing the contents of records or the numbers of records can be done,but not very efficiently. Accessing the contents of some specific records can be done,but not very efficiently.Sequential Characteristics Sequential Characteristics • One usually uses sequential files for writing and reading data that is not changed later and that is read all at once. It is the most efficient way of storing files which have variable length records. • Changing the contents of records or the numbers of records can be done, but not very efficiently. • Accessing the contents of some specific records can be done, but not very efficiently