1Z0-061 · Question #311
Consider these three statements: create view v1 as select department_id,department_name,last_name from departments join employees using (department_id); select department_name,last_name from v1…
The correct answer is D. Sad but true. Views do not help performance. A is wrong because a view is only a SELECT statement; it doesn't prerun the query. B is wrong because the Oracle optimizer will sort out any differences in syntax. C is wrong because, although views are precompiled, this doesn't affect the speed of compiling a user's statement.
Question
Consider these three statements:
create view v1 as select department_id,department_name,last_name from departments join employees using (department_id); select department_name,last_name from v1 where department_id=20; select d.department_name,e.last_name from departments d, employees ewhere d.department_id=e.department_id and d.department_id=20; The first query will be quicker than the second because (choose the best answer):
Options
- AThe view has already done the work of joining the tables.
- BThe view uses ISO standard join syntax, which is faster than the Oracle join syntax used in the
- CThe view is precompiled, so the first query requires less dynamic compilation than the second
- DSad but true. Views do not help performance.
How the community answered
(38 responses)- A11% (4)
- B5% (2)
- C3% (1)
- D82% (31)
Explanation
A is wrong because a view is only a SELECT statement; it doesn't prerun the query. B is wrong because the Oracle optimizer will sort out any differences in syntax. C is wrong because, although views are precompiled, this doesn't affect the speed of compiling a user's statement.
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