READ Free Dumps For Oracle- 1z0-007
| Question ID 7917 | In which scenario would index be most useful?
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| Option A | The indexed column is declared as NOT NULL.
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| Option B | The indexed columns are used in the FROM clause.
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| Option C | The indexed columns are part of an expression.
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| Option D | The indexed column contains a wide range of values.
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| Correct Answer | D |
Explanation Explanation/Reference: Explanation: Index will be useful if the indexed column contains a wide range of values. Especially B-tree indexes will work better for tables with a wide range of values. But for tables just with some distinct values bitmap indexes will be more helpful. Incorrect Answers A: Oracle automatically creates index for NOT NULL columns, so you don't need create an index yourself. B: There are only table names in the FROM clause, not columns. C: Index may be will not work if the indexed columns are part of an expression. You need to avoid expressions if you want to use index. OCP Introduction to Oracle 9i: SQL Exam Guide, Jason Couchman, p. 322-331 Chapter 3: Creating Other Database Objects in Oracle
| Question ID 7918 | Which SQL statement generates the alias Annual Salary for the calculated column SALARY*12?
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| Option A | SELECT ename, salary*12 'Annual Salary' FROM employees;
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| Option B | SELECT ename, salary*12 "Annual Salary" FROM employees;
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| Option C | SELECT ename, salary*12 AS Annual Salary FROM employees;
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| Option D | SELECT ename, salary*12 AS INITCAP("ANNUAL SALARY") FROM employees
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| Correct Answer | B |
Explanation Explanation/Reference: Explanation: This SQL statement provides correct syntax to generate the alias Annual Salary for the calculated column SALARY*12. Incorrect Answers A: Alias can be surrounded with double quotation marks, not with single. Oracle error will be generated in this case. C: Alias needs to be surrounded with double quotation marks, it cannot just follow by the AS keyword. D: You cannot use any function as alias, so this SQL statement will fail. OCP Introduction to Oracle 9i: SQL Exam Guide, Jason Couchman, p. 33-35 Chapter 1: Overview of Oracle Databases