Computer Science Engineering (CSE) Exam > Computer Science Engineering (CSE) Questions > Consider a table STUDENTS and the following t...
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Consider a table STUDENTS and the following two SQL queries.
Query 1 – DELETE FROM STUDENTS;
Query 2 – TRUNCATE TABLE STUDENTS;
Q. Which of the following is TRUE :
- a)Query 2 will fire any associated triggers whereas Query 1 will not
- b)Both the queries are exactly same
- c)Both the queries remove all rows from the table and this cannot be undone
- d)Only Query 1 requires some other operation to make the removal permanent
Correct answer is option 'D'. Can you explain this answer?
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Consider a table STUDENTS and the following two SQL queries.Query 1 &#...
Both the queries will remove all the rows from the table. But, query 1 can be undone by using rollback whereas query 2 is permanent. Also, DELETE fires all the associated triggers whereas TRUNCATE does not.
Most Upvoted Answer
Consider a table STUDENTS and the following two SQL queries.Query 1 &#...
Understanding the Difference Between DELETE and TRUNCATE
When comparing the two SQL queries, it's essential to understand their mechanics and implications.
1. Query Operations
- DELETE FROM STUDENTS:
- Removes rows one at a time.
- Can have a WHERE clause to specify which rows to delete.
- Fires any DELETE triggers associated with the table.
- TRUNCATE TABLE STUDENTS:
- Removes all rows in a table quickly.
- Resets any auto-increment counters.
- Does not fire triggers associated with the table.
2. Rollback Capability
- DELETE:
- Each row deletion is logged, allowing for a rollback if needed.
- Changes made by this query can be undone if enclosed within a transaction.
- TRUNCATE:
- It is a DDL command and cannot be rolled back if executed outside of a transaction.
- Once executed, the operation is permanent and cannot be undone.
3. Permanent Removal
- Only Query 1 (DELETE):
- Requires a COMMIT statement to make changes permanent if used within a transaction.
- If not committed, changes can be reversed.
- Query 2 (TRUNCATE):
- Is immediately permanent upon execution.
Conclusion
In summary, the correct answer is option 'D' because:
- DELETE requires an explicit COMMIT to finalize the operation in a transactional context, while TRUNCATE is immediately effective and cannot be rolled back. Understanding these differences is vital for managing data integrity and ensuring the intended outcomes when modifying database tables.
When comparing the two SQL queries, it's essential to understand their mechanics and implications.
1. Query Operations
- DELETE FROM STUDENTS:
- Removes rows one at a time.
- Can have a WHERE clause to specify which rows to delete.
- Fires any DELETE triggers associated with the table.
- TRUNCATE TABLE STUDENTS:
- Removes all rows in a table quickly.
- Resets any auto-increment counters.
- Does not fire triggers associated with the table.
2. Rollback Capability
- DELETE:
- Each row deletion is logged, allowing for a rollback if needed.
- Changes made by this query can be undone if enclosed within a transaction.
- TRUNCATE:
- It is a DDL command and cannot be rolled back if executed outside of a transaction.
- Once executed, the operation is permanent and cannot be undone.
3. Permanent Removal
- Only Query 1 (DELETE):
- Requires a COMMIT statement to make changes permanent if used within a transaction.
- If not committed, changes can be reversed.
- Query 2 (TRUNCATE):
- Is immediately permanent upon execution.
Conclusion
In summary, the correct answer is option 'D' because:
- DELETE requires an explicit COMMIT to finalize the operation in a transactional context, while TRUNCATE is immediately effective and cannot be rolled back. Understanding these differences is vital for managing data integrity and ensuring the intended outcomes when modifying database tables.
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Consider a table STUDENTS and the following two SQL queries.Query 1 – DELETE FROM STUDENTS;Query 2 – TRUNCATE TABLE STUDENTS;Q. Which of the following is TRUE :a)Query 2 will fire any associated triggers whereas Query 1 will notb)Both the queries are exactly samec)Both the queries remove all rows from the table and this cannot be undoned)Only Query 1 requires some other operation to make the removal permanentCorrect answer is option 'D'. Can you explain this answer?
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Consider a table STUDENTS and the following two SQL queries.Query 1 – DELETE FROM STUDENTS;Query 2 – TRUNCATE TABLE STUDENTS;Q. Which of the following is TRUE :a)Query 2 will fire any associated triggers whereas Query 1 will notb)Both the queries are exactly samec)Both the queries remove all rows from the table and this cannot be undoned)Only Query 1 requires some other operation to make the removal permanentCorrect answer is option 'D'. Can you explain this answer? for Computer Science Engineering (CSE) 2024 is part of Computer Science Engineering (CSE) preparation. The Question and answers have been prepared according to the Computer Science Engineering (CSE) exam syllabus. Information about Consider a table STUDENTS and the following two SQL queries.Query 1 – DELETE FROM STUDENTS;Query 2 – TRUNCATE TABLE STUDENTS;Q. Which of the following is TRUE :a)Query 2 will fire any associated triggers whereas Query 1 will notb)Both the queries are exactly samec)Both the queries remove all rows from the table and this cannot be undoned)Only Query 1 requires some other operation to make the removal permanentCorrect answer is option 'D'. Can you explain this answer? covers all topics & solutions for Computer Science Engineering (CSE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Consider a table STUDENTS and the following two SQL queries.Query 1 – DELETE FROM STUDENTS;Query 2 – TRUNCATE TABLE STUDENTS;Q. Which of the following is TRUE :a)Query 2 will fire any associated triggers whereas Query 1 will notb)Both the queries are exactly samec)Both the queries remove all rows from the table and this cannot be undoned)Only Query 1 requires some other operation to make the removal permanentCorrect answer is option 'D'. Can you explain this answer?.
Consider a table STUDENTS and the following two SQL queries.Query 1 – DELETE FROM STUDENTS;Query 2 – TRUNCATE TABLE STUDENTS;Q. Which of the following is TRUE :a)Query 2 will fire any associated triggers whereas Query 1 will notb)Both the queries are exactly samec)Both the queries remove all rows from the table and this cannot be undoned)Only Query 1 requires some other operation to make the removal permanentCorrect answer is option 'D'. Can you explain this answer? for Computer Science Engineering (CSE) 2024 is part of Computer Science Engineering (CSE) preparation. The Question and answers have been prepared according to the Computer Science Engineering (CSE) exam syllabus. Information about Consider a table STUDENTS and the following two SQL queries.Query 1 – DELETE FROM STUDENTS;Query 2 – TRUNCATE TABLE STUDENTS;Q. Which of the following is TRUE :a)Query 2 will fire any associated triggers whereas Query 1 will notb)Both the queries are exactly samec)Both the queries remove all rows from the table and this cannot be undoned)Only Query 1 requires some other operation to make the removal permanentCorrect answer is option 'D'. Can you explain this answer? covers all topics & solutions for Computer Science Engineering (CSE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Consider a table STUDENTS and the following two SQL queries.Query 1 – DELETE FROM STUDENTS;Query 2 – TRUNCATE TABLE STUDENTS;Q. Which of the following is TRUE :a)Query 2 will fire any associated triggers whereas Query 1 will notb)Both the queries are exactly samec)Both the queries remove all rows from the table and this cannot be undoned)Only Query 1 requires some other operation to make the removal permanentCorrect answer is option 'D'. Can you explain this answer?.
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Consider a table STUDENTS and the following two SQL queries.Query 1 – DELETE FROM STUDENTS;Query 2 – TRUNCATE TABLE STUDENTS;Q. Which of the following is TRUE :a)Query 2 will fire any associated triggers whereas Query 1 will notb)Both the queries are exactly samec)Both the queries remove all rows from the table and this cannot be undoned)Only Query 1 requires some other operation to make the removal permanentCorrect answer is option 'D'. Can you explain this answer?, a detailed solution for Consider a table STUDENTS and the following two SQL queries.Query 1 – DELETE FROM STUDENTS;Query 2 – TRUNCATE TABLE STUDENTS;Q. Which of the following is TRUE :a)Query 2 will fire any associated triggers whereas Query 1 will notb)Both the queries are exactly samec)Both the queries remove all rows from the table and this cannot be undoned)Only Query 1 requires some other operation to make the removal permanentCorrect answer is option 'D'. Can you explain this answer? has been provided alongside types of Consider a table STUDENTS and the following two SQL queries.Query 1 – DELETE FROM STUDENTS;Query 2 – TRUNCATE TABLE STUDENTS;Q. Which of the following is TRUE :a)Query 2 will fire any associated triggers whereas Query 1 will notb)Both the queries are exactly samec)Both the queries remove all rows from the table and this cannot be undoned)Only Query 1 requires some other operation to make the removal permanentCorrect answer is option 'D'. Can you explain this answer? theory, EduRev gives you an
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