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databases Online Quiz - 186

Description: databases Online Quiz - 186
Number of Questions: 20
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Tags: databases
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A subquery can be used to _________.

technology databases

  1. Create groups of data

  2. Sort data in a specific order

  3. Convert data to a different format

  4. Retrieve data based on an unknown condition

Show answer
Correct Option: D

AI Explanation

To answer this question, you need to understand the concept of subqueries in SQL.

A subquery is a query that is nested inside another query. It can be used to retrieve data based on an unknown condition, which makes option D the correct answer.

Let's go through each option to understand why it is correct or incorrect:

Option A) Create groups of data - This option is incorrect because creating groups of data is typically done using the GROUP BY clause, not a subquery.

Option B) Sort data in a specific order - This option is incorrect because sorting data is typically done using the ORDER BY clause, not a subquery.

Option C) Convert data to a different format - This option is incorrect because converting data to a different format is typically done using functions like CAST or CONVERT, not a subquery.

Option D) Retrieve data based on an unknown condition - This option is correct because a subquery can be used to retrieve data based on an unknown condition. The subquery can be used within the WHERE clause to filter the data based on a condition that is dynamically determined.

Therefore, the correct answer is D.

what does the sql code -922 represents?
technology databases

  1. query will retrieve only one row

  2. authorization failure

  3. no such code available

  4. rollback

Show answer
Correct Option: B
Explanation:

To answer this question, we need to know the context in which the SQL code -922 is being used. SQL codes are specific error or informational messages generated by the database management system (DBMS) when it encounters certain conditions or situations. Without context, it is difficult to determine the exact meaning of a particular SQL code.

However, in general, SQL code -922 is associated with authorization failures. This means that the user attempting to execute a particular SQL statement does not have the required permissions or privileges to perform the operation. The exact meaning and resolution of the error will depend on the specific DBMS being used and the context in which the error occurred.

Therefore, the correct answer is:

The Answer is: B. authorization failure.

choose the environments which can access DB2
technology databases

  1. TSO

  2. IMC

  3. CICS

  4. None of the above

Show answer
Correct Option: A,C

5 rows are inserted to a DB2 Table. Next 3 of those are updated, then a rollback is issued. What would happen when the rollback is issued?

technology databases

  1. returns 5 rows

  2. returns 3 rows

  3. returns all 8rows

  4. none

Show answer
Correct Option: B

Which are true regarding the use of outer joins?
technology databases

  1. You cannot use IN operator in a condition that involves an outerjoin

  2. You use (+) on both sides of the WHERE condition to perform an outerjoin

  3. You use (*) on both sides of the WHERE condition to perform an outerjoin

  4. You use an outerjoin to see only the rows that do not meet the join condition

  5. In the WHERE condition, you use (+) following the name of the column in the table

  6. You cannot link a condition that is involved in an outerjoin to another condition by

Show answer
Correct Option: D,E,F

Which two statements complete a transaction? (Choose two)
technology databases

  1. DELETE employees;

  2. DESCRIBE employees;

  3. ROLLBACK TO SAVEPOINT C;

  4. GRANT SELECT ON employees TO SCOTT;

  5. ALTER TABLE employees SET UNUSED COLUMN sal;

  6. Select MAX(sal) FROM employees WHERE department_id = 20;

Show answer
Correct Option: C,E

Which two are true about aggregate functions? (Choose two.)
technology databases

  1. You can use aggregate functions in any clause of a SELECT statement.

  2. You can use aggregate functions only in the column list of the SELECT clause and in the WHERE clause of a SELECT statement.

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

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

  5. You can use aggregate functions on a table, only by grouping the whole table as one single group.

  6. You cannot group the rows of a table by more than one column while using aggregate functions.

Show answer
Correct Option: C,D

Which of the following is not a valid aggregate function
technology databases

  1. COUNT

  2. SUM

  3. COMPUTE

  4. MIN

Show answer
Correct Option: C
Explanation:

To solve this question, the user needs to have knowledge about aggregate functions in SQL.

Aggregate functions are used to perform calculations on a set of values to return a single value.

Now let's go through each option and explain why it is right or wrong:

A. COUNT: This is a valid aggregate function in SQL. It returns the number of rows that match a specified condition.

B. SUM: This is a valid aggregate function in SQL. It returns the sum of a set of values.

C. COMPUTE: This is not a valid aggregate function in SQL. There is no such function as COMPUTE in SQL.

D. MIN: This is a valid aggregate function in SQL. It returns the minimum value of a set of values.

Therefore, the answer is:

The Answer is: C

To use a FETCH staement with a cursor you always have to supply an explicit direction such next or prior.
technology databases

  1. TRUE

  2. FALSE

  3. BOTH

  4. NONE

Show answer
Correct Option: B

Which of the following is non-PL/SQL variable?
technology databases

  1. Scalar

  2. LOB

  3. Reference

  4. host

Show answer
Correct Option: D

PL/SQL does not support boolean variables
technology databases

  1. True

  2. False

Show answer
Correct Option: B

Which four are valid Oracle constraint types?
technology databases

  1. CASCADE

  2. UNIQUE

  3. NONUNIQUE

  4. CHECK

  5. PRIMARY KEY

  6. NOT NULL

Show answer
Correct Option: B,D,E,F

Which is an iSQL*PLUS command?
technology databases

  1. INSERT

  2. UPDATE

  3. SELECT

  4. DESCRIBE

  5. DELETE

  6. RENAME

Show answer
Correct Option: D

Top N analysis requires _____ and ______?(Choose two)

technology databases

  1. the use of rowed

  2. a GROUP BY clause

  3. an ORDER BY clause

  4. only an inline view

  5. an inline view and an outer query

Show answer
Correct Option: C,E

Which constraint can be defined only at the column level?
technology databases

  1. UNIQUE

  2. NOT NULL

  3. CHECK

  4. PRIMARY KEY

  5. FOREIGN KEY

Show answer
Correct Option: B

What does the FORCE option for creating a view do?

technology databases

  1. creates a view with constraints

  2. creates a view even if the underlying parent table has constraints

  3. creates a view in another schema even if you don't have privileges

  4. creates a view regardless of whether or not the base tables exist

Show answer
Correct Option: D

The user Alice wants to grant all users query privileges on her DEPT table. Which SQL statement accomplishes this?
technology databases

  1. GRANT select ON dept TO ALL USERS;

  2. GRANT select ON dept TO ALL;

  3. GRANT QUERY ON dept TO ALL USERS;

  4. GRANT select ON dept TO PUBLIC;

Show answer
Correct Option: D
Explanation:

To solve this question, the user needs to know the SQL syntax for granting privileges to users and the difference between "ALL USERS" and "PUBLIC".

Now, let's go through each option and explain why it is right or wrong:

A. GRANT select ON dept TO ALL USERS; This option is incorrect because the correct keyword to grant privileges to all users is "PUBLIC" instead of "ALL USERS". Also, "QUERY" is not a valid keyword, and the correct keyword to grant query privileges is "SELECT". Therefore, option A is incorrect.

B. GRANT select ON dept TO ALL; This option is incorrect because the correct keyword to grant query privileges is "SELECT" instead of "QUERY". Also, "ALL" is not a valid keyword to grant privileges to all users, and the correct keyword is "PUBLIC". Therefore, option B is incorrect.

C. GRANT QUERY ON dept TO ALL USERS; This option is incorrect because "QUERY" is not a valid keyword to grant privileges, and the correct keyword is "SELECT". Also, "ALL USERS" is not a valid keyword to grant privileges to all users, and the correct keyword is "PUBLIC". Therefore, option C is incorrect.

D. GRANT select ON dept TO PUBLIC; This option is correct. The correct keyword to grant select (query) privileges is "SELECT". The keyword "PUBLIC" is used to grant privileges to all users. Therefore, option D is the correct answer.

The Answer is: D

Which three are true?(Choose three)
technology databases

  1. A MERGE statement is used to merge the data of one table with data from another

  2. A MERGE statement replaces the data of one table with that of another

  3. A MERGE statement can be used to insert new rows into a table

  4. A MERGE statement can be used to update existing rows in a table

Show answer
Correct Option: A,B,C

What is true about Sequences?

technology databases

  1. Once created, a sequence belongs to a specific schema

  2. Once created, a sequence is linked to a specific table

  3. Once created, a sequence is automatically available to all users

  4. Only the DBA can control which squence is used by certain a table

  5. Once created, a sequence is automatically in all INSERT and UPDATE statements

Show answer
Correct Option: C

John has created a procedure named SALARY_CALC. Which SQL query allows him to view the text of the procedure?
technology databases

  1. SELECT text FROM user_source WHERE name ='SALARY_CALC';

  2. SELECT * FROM user_source WHERE source_name ='salary_calc';

  3. SELECT * FROM user_objects WHERE object_name = 'SALARY_CALC';

  4. SELECT text FROM user_source WHERE name='SALARY_CALC' AND owner ='JOHN';

Show answer
Correct Option: A
Explanation:

To solve this question, the user needs to know the structure of the system tables in Oracle database where all the objects are stored.

Option A is correct. This query will return the text of the procedure SALARY_CALC. The user_source view contains all the source code for the stored procedures, functions, and triggers in the current user's schema. By specifying the name of the procedure in the WHERE clause, the query filters the result set to only show the source code for the SALARY_CALC procedure.

Option B is incorrect. There is no column named "source_name" in the user_source view. Therefore, this query will return an error.

Option C is incorrect. The user_objects view contains information about all objects in the current user's schema, including tables, views, indexes, and procedures. However, the view does not contain the source code for the procedures. Therefore, this query will not return any rows.

Option D is incorrect. The condition "AND owner='JOHN'" is unnecessary because the user_source view only contains source code for the objects owned by the current user. Therefore, this query will return the same result as option A, but with an unnecessary condition.

The Answer is: A. SELECT text FROM user_source WHERE name ='SALARY_CALC';

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