Tag: databases

Questions Related to databases

Which /SQL*Plus feature can be used to replace values in the WHERE clause?

technology databases

  1. Substitution variables

  2. Replacement variables

  3. Prompt variables

  4. Instead-of variables

Show answer
Correct Option: A
Explanation:

To solve this question, the user needs to know the basic functionalities of SQL*Plus.

The feature that can be used to replace values in the WHERE clause is Substitution variables.

Option A is correct. Substitution variables can be used to replace values in the WHERE clause at runtime. They begin with an ampersand (&) and can be used to replace any part of the SQL query, including the WHERE clause.

Option B is incorrect. Replacement variables are not a feature of SQL*Plus, and they cannot be used to replace values in the WHERE clause.

Option C is incorrect. Prompt variables are also not a feature of SQL*Plus and cannot be used to replace values in the WHERE clause.

Option D is incorrect. Instead-of variables are not a feature of SQL*Plus and cannot be used to replace values in the WHERE clause.

The answer is: A

You want to use SQL*Plus to connect to the oracle database. Which of the following choices does not indicate a component you must specify when logging into the oracle?

technology databases

  1. The SQL*Plus Keyword.

  2. The username

  3. The password

  4. The database name

Show answer
Correct Option: D

AI Explanation

To answer this question, you need to understand the components required to connect to an Oracle database using SQL*Plus.

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

Option A) The SQL*Plus Keyword - This option is incorrect because you need to specify the SQL*Plus keyword, such as "sqlplus", to indicate that you want to use SQL*Plus for database connection.

Option B) The username - This option is correct because you must specify a valid username to connect to the Oracle database. The username identifies the user account that you want to use for the connection.

Option C) The password - This option is correct because you must provide the correct password associated with the specified username to establish a successful connection to the Oracle database.

Option D) The database name - This option is incorrect because you must specify the database name as part of the connection information. The database name identifies the specific Oracle database you want to connect to.

The correct answer is D) The database name. This option does not indicate a component you must specify when logging into the Oracle database using SQL*Plus.

Evaluate the SQL statement: SELECT LPAD (salary,10,*) FROM EMP WHERE EMP_ID = 1001; If the employee with the EMP_ID 1001 has a salary of 17000, what is displayed?

technology databases

  1. 17000.00

  2. 17000*****

  3. ****170.00

  4. **17000.00

  5. an error statement

Show answer
Correct Option: C
Explanation:

To understand this SQL statement, the user should know about the LPAD function, which pads a string with a specified character until the string reaches a specified length. In this case, the salary column will be padded with asterisks (*) until it is 10 characters long.

The WHERE clause restricts the query to employees with an EMP_ID of 1001.

Assuming the employee with EMP_ID 1001 has a salary of 17000, the LPAD function will pad the salary with asterisks () until it has a length of 10 characters, resulting in the string "***17000". Therefore, the correct answer is:

The Answer is: A. ****170.00

For which action can you use the TO_DATE function?

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  1. Convert any date literal to a date

  2. Convert any numeric literal to a date

  3. Convert any character literal to a date

  4. Convert any date to a character literal

  5. Format ’10-JAN-99’ to ‘January 10 1999’

Show answer
Correct Option: C
Explanation:

To use the TO_DATE function, you need to know the purpose of the function and what it does. The TO_DATE function is used to convert a character string to a date format. The user needs to know that this function is used to convert a character string to a date format.

Now, let's evaluate each option to determine which one uses the TO_DATE function correctly:

A. Convert any date literal to a date - This option is incorrect. The TO_DATE function is used to convert character literals to a date format, not date literals.

B. Convert any numeric literal to a date - This option is incorrect. The TO_DATE function is used for character literals, not numeric literals.

C. Convert any character literal to a date - This option is correct. The TO_DATE function is used to convert character literals to a date format.

D. Convert any date to a character literal - This option is incorrect. The TO_CHAR function is used to convert dates to character literals, not the TO_DATE function.

E. Format ’10-JAN-99’ to ‘January 10 1999’ - This option is incorrect. The TO_CHAR function is used to format dates, not the TO_DATE function.

Therefore, the answer is: C. Convert any character literal to a date

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

Which two are types of functions available in SQL?

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  1. String

  2. Character

  3. Integer

  4. Calander

  5. Numeric

  6. Translation

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Correct Option: B,E

Which two statements are true about constraints?

technology databases

  1. The UNIQUE constraint does not permit a null value for the column.

  2. A UNIQUE index gets created for columns with PRIMARY KEY and UNIQUE constraints.

  3. The PRIMARY KEY and FOREIGN KEY constraints create a UNIQUE index.

  4. The NOT NULL constraint ensures that null values are not permitted for the column.

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) The UNIQUE constraint does not permit a null value for the column. This option is correct. The UNIQUE constraint ensures that each value in the column is unique. It also does not permit a null value for the column, meaning that the column must have a non-null value for each row.

Option B) A UNIQUE index gets created for columns with PRIMARY KEY and UNIQUE constraints. This option is incorrect. While it is true that a UNIQUE index is created for columns with UNIQUE constraints, it is not true for columns with PRIMARY KEY constraints. A PRIMARY KEY constraint automatically creates a unique index, but a UNIQUE constraint creates a separate unique index.

Option C) The PRIMARY KEY and FOREIGN KEY constraints create a UNIQUE index. This option is incorrect. While it is true that a PRIMARY KEY constraint automatically creates a unique index, a FOREIGN KEY constraint does not create a unique index. A FOREIGN KEY constraint is used to establish a relationship between two tables.

Option D) The NOT NULL constraint ensures that null values are not permitted for the column. This option is correct. The NOT NULL constraint ensures that the column must have a non-null value for each row. It does not allow null values to be inserted into the column.

The correct answer is A and D. These options are correct because the UNIQUE constraint does not permit a null value for the column, and the NOT NULL constraint ensures that null values are not permitted for the column.

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

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  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

Which constraint can be defined only at the column level?

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  1. Unique

  2. Not null

  3. Check

  4. Primary key

  5. Foreign key

Show answer
Correct Option: B

AI Explanation

To answer this question, let's go through each option to understand which constraint can be defined only at the column level:

Option A) Unique - The unique constraint can be defined at both the column level and the table level. So, this option is incorrect.

Option B) Not null - The not null constraint can only be defined at the column level. This option is correct.

Option C) Check - The check constraint can be defined at both the column level and the table level. So, this option is incorrect.

Option D) Primary key - The primary key constraint can be defined at both the column level and the table level. So, this option is incorrect.

Option E) Foreign key - The foreign key constraint can be defined at both the column level and the table level. So, this option is incorrect.

The correct answer is option B) Not null. This constraint can only be defined at the column level.

Which best describes an inline view?

technology databases

  1. a schema object

  2. a subquery that can contain an ORDER BY clause

  3. another name for a view that contains group functions

  4. a subquery that is part of the FROM clause of another query

Show answer
Correct Option: D