一起答
单选

数据的逻辑独立性是指当数据库的(57)。

  • A.模式发生改变时,数据的逻辑结构不需要改变
  • B.模式发生改变时,数据的用户结构不需要改变
  • C.外模式发生改变时,数据的逻辑结构不需要改变
  • D.内模式发生改变时,数据的用户结构不需要改变
参考答案
查看试卷详情
相关试题
  1. (99)

    • A.add
    • B.combination
    • C.difference
    • D.condition
  2. (98)

    • A.earlier
    • B.front
    • C.backward
    • D.later
  3. (96)

    • A.past
    • B.other
    • C.rest
    • D.host
  4. (97)

    • A.voice
    • B.mass
    • C.quantity
    • D.quality
  5. By using MP3, a 600M-byte music CD can be(70)to 50M bytes or less. It can be streamed(downloaded in chunks)so that you can begin listening to the opening bars while the(71)of the file arrives in the background. And, most important, MP3 music files retain good listening(72)that(73)compression schemes lacked. That(74)of features makes accessing and distributing music on the Web practical for the first time.

    • A.pressed
    • B.compressed
    • C.press
    • D.compress
  6. (94)

    • A.execute
    • B.interrupt
    • C.run
    • D.maintain
  7. The following suggestions increase program's(73)and make them easier to(74):

      Use a standard indention technique, blank lines, form. feeds, and spaces.

      Insert plenty of comments into your code.

    • A.security
    • B.reliability
    • C.readability
    • D.usability
  8. (92)

    • A.locates
    • B.allocates
    • C.looks for
    • D.finds
  9. In C language,(70)variables have to be defined outside of any function, this(71)actual storage for it.

    • A.internal
    • B.export
    • C.output
    • D.external
  10. when a string constant is written in C program, the eompiler creates(75)of characters containing the characters of the string, and terminating it with "\0".

    • A.a group
    • B.an array
    • C.a set
    • D.a series