BIA5 - WJIDF PDF

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most of join is inner join; left & right join usually for negative (not equal to… etc.) The entity relationship diagrams represent the ________ view of the database. a. condensed b. physical c. logical d. conceptual Data redundancy produces: a. slower lookups b. robust design c. efficient storage use d. dataintegrityproblems Which of the following variable name will result in an error? 【c,d】 a. Last_name b. andn c. begin d. 34sdfsdfksfldkjlsjdfljsdkjflsfdkjlsjflsjdflsjdlsjfsldjsljfdslksdf Which of the following is an object privilege? a. Create session b. Drop user c. Insert any table d. update SECTION B 1. DBA: DA: 2. Tablespace 3. P1 4. a.2 combined index on (EMP_SEX, EMP_AREACODE) and (EMP_LNAME, EMP_FNAME) b.the data sparsity of EMP_SEX column is 2 : ‘F’ or ‘M’, the type of index should be bitmap, because the value stored in EMP_SEX column is in low sparsity. 20. a. Three phases: Parsing phase, Execution phase, Fetching phase. b. Query optimization take place in Parsing phase…….. 21. PL/SQL 的好处 1.Better Performance: Without PL/SQL, Oracle must process SQL statements one at a time. Programs that issue many SQL statements require multiple calls to the database, resulting in significant network and performance overhead. 2.Higher Productivity: PL/SQL lets you write very compact code for manipulating data. In the same way thatscripting languages such as Perl can read, transform, and write data from files, PL/SQL can query, transform, and update data in a database. PL/SQL saves time on design and debugging by offering a full range of software-engineering features, such as exception handling, encapsulation, data hiding, and object-oriented datatypes.

22. 4, 2, 1/5, 3 23. 代码注入 a. Leakage of sensitive information. Reputation decline. Modification of sensitive information. Loss of control of db server. Data loss. Denial of service. b. Reduce the attack surface Avoid dynamic SQL with concatenated input Use bind arguments Filter and sanitize input 24. NoSQL 的好处 25.PGA, SGA

SECTION C 26. ER-Diagram 27. a. select pname1 From Follows Where pname2 = ‘Obama’; b. select distinct t.tagname from persontweets p, tweettag t where p.pname = ‘Obama’ and p.tid = t.tid; c. select t.tagname from follows f, persontweets p, tweettag t where f.pname1 = ‘Obama’ and p.pname = f.pname2 and p.tid = t.tid d. select tid from (select tid, count(tagname) as numtag from tweettag group by tid order by numtag desc) ——把 每个 tweet 里面 的 tag 数出 来， 并按 照 tweet 分组。 where rownum = 1 e. select f1.pname2, f2.pname2 from follows f1 join follows f2 on f1.pname1 = f2.pname1 where f1.pname2 >

f2.pname2

A database is a collection of information that is organized so that it can easily be accessed, managed, and updated. In one view, databases can be classified according to types of content: bibliographic, full-text, numeric, and images.

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