Tag: technology

Questions Related to technology

Which of the following can be a valid column name?

technology databases

  1. Column

  2. 123_Invoices

  3. Catch_#22

  4. #Invoices

  5. None of the above

Show answer
Correct Option: C

When you press Alt + V + Z + 2, the worksheet view zooms to ____ %
technology databases

  1. 2%

  2. 20%

  3. 25%

  4. 200%

Show answer
Correct Option: C

The quickest way of creating a chart (graph) in excel is by choosing a data range and pressing
technology databases

  1. Shift + F1

  2. Ctrl + 1

  3. F11 or ALT+F1

  4. Ctrl + Shift + F1

Show answer
Correct Option: C

When you press Ctrl + Shift+ 1
technology databases

  1. The cell gets formatted to Number category with 2 decimal places

  2. The cell gets formatted to Number category with 4 decimal places

  3. The cell gets formatted into different font

  4. Nothing happens

Show answer
Correct Option: A

The TRUNCATE command writes user data to Rollback segments
technology databases

  1. True

  2. False

Show answer
Correct Option: B

To produce a meaningful result set without any cartesian products, what is the minimum number of conditions that should appear in the WHERE clause of a that joins 'N' tables?
technology databases

  1. 4

  2. 3

  3. N - 1

  4. N + 1

Show answer
Correct Option: C
Explanation:

To solve this question, the user needs to have a basic understanding of SQL joins and how to prevent cartesian products.

When joining N tables, the minimum number of conditions that should appear in the WHERE clause to produce a meaningful result set without any cartesian products is N - 1. This is because each join condition connects two tables, and N tables can be connected by N - 1 join conditions.

Option A (4) and Option B (3) are not correct because they provide specific numbers of conditions that do not apply to all cases. The number of conditions needed depends on the number of tables being joined, which is not specified in the question.

Option C (N - 1) is correct, as explained above.

Option D (N + 1) is incorrect because adding an additional condition would result in a more restrictive query, potentially excluding valid results.

Therefore, the answer is: C. N - 1.

When a user creates an object without a TABLESPACE clause, where will Oracle store the segment?

technology databases

  1. System tablespace

  2. Users tablespace

  3. Default tablespace for the user

  4. Oracle will give an error

Show answer
Correct Option: C

Which Oracle access method is the fastest way for Oracle to retrieve a single row?

technology databases

  1. Primary key access

  2. Access via unique index

  3. Table access by ROWID

  4. Full table scan

Show answer
Correct Option: C

AI Explanation

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

Option A) Primary key access - This option is a fast way for Oracle to retrieve a single row. When a table has a primary key defined, Oracle can use the primary key index to directly access the specific row based on its primary key value.

Option B) Access via unique index - This option is also a fast way for Oracle to retrieve a single row. When a table has a unique index defined on a column, Oracle can use the unique index to directly access the specific row based on its unique index value.

Option C) Table access by ROWID - This option is the fastest way for Oracle to retrieve a single row. The ROWID is a unique identifier for each row in a table, and Oracle can use the ROWID to directly access the specific row without needing to use an index.

Option D) Full table scan - This option is not the fastest way for Oracle to retrieve a single row. A full table scan involves reading every row in the table, which can be time-consuming and resource-intensive. It is generally used when retrieving multiple rows or when there is no appropriate index available.

The correct answer is C) Table access by ROWID. This option is the fastest way for Oracle to retrieve a single row because it directly accesses the specific row using its unique ROWID identifier.

Tables, views , incexes are all part of database objects
technology databases

  1. True

  2. False

Show answer
Correct Option: A

Which command will delete all data from a table and will not write to the rollback segment?
technology databases

  1. DROP

  2. DELETE

  3. CASCADE

  4. TRUNCATE

Show answer
Correct Option: D
Explanation:

To solve this question, the user needs to know the basic SQL commands for deleting data from a table.

Option A: DROP is used to delete an entire table, not just its data. This option is incorrect.

Option B: DELETE is used to delete data from a table. However, it writes the deleted data to the rollback segment in case it needs to be recovered later. This option is incorrect.

Option C: CASCADE is an option used with the DROP command to delete all objects that depend on the specified object before dropping that object. This option is incorrect.

Option D: TRUNCATE is used to delete all data from a table without logging the individual row deletions. It does not write the deleted data to the rollback segment, making it a faster operation compared to DELETE. This option is correct.

Therefore, the answer is: D. TRUNCATE.