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databases Online Quiz - 227

Description: databases Online Quiz - 227
Number of Questions: 20
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Tags: databases
Attempted 0/20 Correct 0 Score 0
  1. Primary key access

  2. Access via unique index

  3. Table access by ROWID

  4. Full table scan


Correct Option: C
  1. DROP

  2. DELETE

  3. CASCADE

  4. TRUNCATE


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.

  1. Programming technique

  2. Automatically used in all prpgramme

  3. PL/SQL compiler directive

  4. All of the above


Correct Option: C
  1. queeing

  2. piping

  3. Autonomus transaction

  4. Host I/O


Correct Option: B

Which is true for ROWID% data type

  1. Binary data upto 4GB

  2. Character data upto 4 GB

  3. A hexadecimal string representing the unique address of a row in its table

  4. Binary data stored in an external file


Correct Option: C
Explanation:

To solve this question, the user needs to know about the ROWID data type in databases.

The ROWID is a pseudo column added by Oracle to all tables, which stores the row's unique identifier. The ROWID is represented in hexadecimal format, and it uniquely identifies each row in a table.

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

A. Binary data upto 4GB: This option is incorrect because ROWID is not a data type that stores binary data.

B. Character data upto 4 GB: This option is incorrect because ROWID is not a data type that stores character data.

C. A hexadecimal string representing the unique address of a row in its table: This option is correct. The ROWID data type stores a hexadecimal string that represents the unique address of a row in its table.

D. Binary data stored in an external file: This option is incorrect because ROWID is not a data type that stores binary data in an external file.

The Answer is: C

What can be used in a SELECT statement to obtain search criteria for the SELECT statement?

  1. HAVING clause

  2. ORDER BY clause

  3. Subquery

  4. GROUP BY clause


Correct Option: C
  1. exec command

  2. / command

  3. execute command

  4. None of these


Correct Option: B

Which database model allows you to store and execute a PL/SQL program as part of an object?

  1. Hierarchical

  2. Relational

  3. Object Relational

  4. Network


Correct Option: C
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