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1.All numbers are assumed to be written in decimal notation unless otherwise indicated.

2.A loop invariant for a while statement

多选题

1.Drawbacks of file-processing system：（ ）

A. Data redundancy and inconsistency B. Maintain atomicity of updates

C. Data isolation D. High concurrent access

2.Which items can determine all attributes in a relation

A. Superkey B. Foreign key C. Candidate key

D. Primary key E. Full key F. Search key

3.Which is the non-procedural language?

A. Relational Algebra B. C C. SQL

D. Tuple Relational Calculus E. Domain Relational Calculus

4. Five basic relational algebra operations are _______, others can be derived from these operations.

/

5.ADBA`s duties are:

A. Security and integrity control

B. Performance monitoring, analyzing, and tuning

C. database restoration and recovery

D. database reforming and restructuring

E. transaction processing and concurrency control

6. In a relational database, given R, U={A,B,C}, F={A->B, B->C, C->A}, a decomposition of R is p={AB，BC}，and the decomposition is:

A. lossless-join, dependency preserving B. lossless-join, not dependency preserving

C. lossy-join, dependency preserving D.lossy-join, not dependency preserving

7. For the following schedules of three transactions in concurrency control, the serializable schedules are:

内容过长，仅展示头部和尾部部分文字预览，全文请查看图片预览。 of the relationship set is the primary key of the “n”side entity set;

C. a binary 1: n relationship set can be united with the “1”side entity set, and translated into one relation;

D. a binary 1: n relationship set can be united with the “n”side entity set, and translated into one relation;

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