Tag: databases

Questions Related to databases

You need to give the MANAGER role the ability to select from, insert into, and modify existing rows in the STUDENT_GRADES table. Anyone given this MANAGER role should be able to pass those privileges on to others. Which statement accomplishes this
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  1. GRANT select, insert, update ON student_grades TO manager

  2. GRANT select, insert, update ON student_grades TO ROLE manager

  3. GRANT select, insert, modify ON student_grades TO manager WITH GRANT OPTION;

  4. GRANT select, insert, update ON student_grades TO manager WITH GRANT OPTION;

Show answer
Correct Option: D

Which are true about aggregate functions? (Choose all that apply)

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  1. You can use aggregate functions in any caluse of the SELECT statement.

  2. You can user aggregate funcitons only in column list of select clause and where clause of select statement.

  3. You can mix single row functions with aggregate functions in the column list of a SELECT statement by grouping on single row columns.

  4. You can pass column names, expressions, constants, or functions as parameter to an aggregate function.

Show answer
Correct Option: A,D

AI Explanation

To answer this question, let's go through each option to understand why it is correct or incorrect:

Option A) You can use aggregate functions in any clause of the SELECT statement. - This option is correct. Aggregate functions can be used in various clauses of the SELECT statement, such as the SELECT clause, WHERE clause, HAVING clause, and ORDER BY clause.

Option B) You can use aggregate functions only in the column list of the SELECT clause and WHERE clause of the SELECT statement. - This option is incorrect. Aggregate functions can be used in multiple clauses of the SELECT statement, not just the column list and WHERE clause.

Option C) You can mix single row functions with aggregate functions in the column list of a SELECT statement by grouping on single row columns. - This option is incorrect. Single row functions and aggregate functions cannot be mixed in the column list without proper grouping. If you want to use both, you need to group the single row columns appropriately.

Option D) You can pass column names, expressions, constants, or functions as parameters to an aggregate function. - This option is correct. Aggregate functions can accept various types of parameters, including column names, expressions, constants, and functions.

The correct answers are A and D. These options are correct because aggregate functions can be used in any clause of the SELECT statement and can accept different types of parameters.

Therefore, the correct answer is A and D.

Which one is a system privilege?
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  1. SELECT

  2. DELETE

  3. EXECUTE

  4. ALTER TABLE

  5. CREATE TABLE

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Correct Option: E

The database administrator of your company created a public synonym called HR for the HUMAN_RESOURCES table of the GENERAL schema, because many users frequently use this table. As a user of the database, you created a table called HR in your schema. What happens when you execute this query? SELECT * FROM HR;
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  1. You obtain the results retrieved from the public synonym HR created by the database administrator.

  2. You obtain the results retrieved from the HR table that belongs to your schema

  3. You get an error message because you cannot retrieve from a table that has the same name as a public synonym

  4. You obtain the results retrieved from both the public synonym HR and the HR table that belongs to your schema, as a Cartesian product.

Show answer
Correct Option: B

Evaluate the SQL statement: 1 SELECT a.emp_name, a.sal, a.dept_id, b.maxsal 2 FROM employees a, 3 (SELECT dept_id, MAX(sal) maxsal 4. FROM employees 5 GROUP BY dept_id) b 6 WHERE a.dept_id = b.dept_id 7 AND a. asl < b. maxsal; What is the result of the statement?

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  1. The statement produces an error at line 1.

  2. The statement produces an error at line 3

  3. The statement produces an error at line 6.

  4. The statement returns the employee name, salary, department ID, and maximum salary earned in the department of the employee for all departments that pay less salary then the maximum salary paid in the company

  5. The statement returns the employee name, salary, department ID, and maximum salary earned in the department of the employee for all employees who earn less than the maximum salary in their department.

Show answer
Correct Option: E
Explanation:

To evaluate the SQL statement, let's go through each line and understand its purpose:

  1. SELECT a.emp_name, a.sal, a.dept_id, b.maxsal: This line selects the employee name, salary, department ID from the "employees" table, and also selects the maximum salary for each department from the subquery aliased as "b".

  2. FROM employees a: This line specifies the "employees" table and aliases it as "a".

  3. (SELECT dept_id, MAX(sal) maxsal FROM employees GROUP BY dept_id) b: This line is a subquery that selects the department ID and maximum salary for each department from the "employees" table. It is aliased as "b".

  4. WHERE a.dept_id = b.dept_id AND a.sal < b.maxsal: This line applies a condition to join the main query with the subquery. It matches the department IDs and ensures that the salary of an employee in department "a" is less than the maximum salary in that department as obtained from the subquery "b".

Now, let's go through the options:

A. The statement produces an error at line 1: This option is incorrect because there is no apparent error in line 1.

B. The statement produces an error at line 3: This option is incorrect because there is no apparent error in line 3.

C. The statement produces an error at line 6: This option is incorrect because there is no line 6 in the SQL statement.

D. The statement returns the employee name, salary, department ID, and maximum salary earned in the department of the employee for all departments that pay less salary than the maximum salary paid in the company: This option is incorrect because the statement does not retrieve the maximum salary paid in the company. It only retrieves the maximum salary for each department.

E. The statement returns the employee name, salary, department ID, and maximum salary earned in the department of the employee for all employees who earn less than the maximum salary in their department: This option is correct. The statement retrieves the employee name, salary, department ID, and the maximum salary earned in the department for all employees who earn less than the maximum salary in their department.

Therefore, the correct answer is option E.

The EMP table contains these columns: LAST NAME VARCHAR2(25) SALARY NUMBER(6,2) DEPARTMENT_ID NUMBER(6) You need to display the employees who have not been assigned to any department. You write the SELECT statement: SELECT LAST_NAME, SALARY, DEPARTMENT_ID FROM EMP WHERE DEPARMENT_ID = NULL; What is true about this SQL statement?
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  1. The SQL statement displays the desired results

  2. The column in the WHERE clause should be changed to display the desired results

  3. The operator in the WHERE clause should be changed to display the desired results

  4. The WHERE clause should be changed to use an outer join to display the desired results

Show answer
Correct Option: C

For which two constraints does the Oracle Server implicitly create a unique index? (Choose two.)
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  1. NOT NULL

  2. PRIMARY KEY

  3. FOREIGN KEY

  4. CHECK

  5. UNIQUE

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Correct Option: B,E

Which two statements about subqueries are true? (Choose two.)
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  1. A single row subquery can retrieve data from only one table

  2. A SQL query statement cannot display data from table B that is referred to in its subquery, unless table B is included in the main query's FROM clause.

  3. A SQL query statement can display data from table B that is referred to in its subquery, without including table B in its own FROM clause.

  4. A single row subquery can retrieve data from more than one table

  5. A single row subquery cannot be used in a condition where the LIKE operator is used for comparison

  6. A multiple-row subquery cannot be used in a condition where the LIKE operator is used for comparison.

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Correct Option: B,D

CREATE TABLE dept(deptno NUMBER(2),dname VARCNAR2(14),1oc VARCNAR2 (13));ROLLBACK;DESCRIBE DEPTWhat is true about the set?
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  1. The DESCRIBE DEPT statement displays the structure of the DEPT table

  2. The ROLLBACK statement frees the storage space occupies by the DEPT table

  3. The DESCRIBE DEPT statement returns an error ORA-04043: object DEPT does not exist

  4. The DESCRIBE DEPT statement displays the structure of the DEPT table only if there is a COMMIT statement introduced before the ROLLBACK statement.

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Correct Option: A

You added a PHONE_NUMBER column of NUMBER data type to an existing EMPLOYEES table. The EMPLOYEES table already contains records of 100 employees. Now, you want to enter the phone numbers of each of the 100 employees into the table. Some of the employees may not have a phone number available. Which data manipulation operation do you perform?
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  1. MERGE

  2. INSERT

  3. UPDATE

  4. ADD

  5. ENTER

Show answer
Correct Option: C