Test by Bikram | Databases | Test 2 | Question: 23

Question

Consider the table ‘employee’ having two columns: 'EmpNo' and 'EmpName'.

Run the following transaction on the table:

COMMIT;
ALTER TABLE employee
ADD PhoneNo varchar(10);
ROLLBACK;

What are the columns in the table after the above operation?

• A. EmpNo  PhoneNo  
• B. EmpNo  EmpName
• C. Same as (B) but will throw an error indicating failed transaction
• D. EmpNo  EmpName  PhoneNo

Comments

@Bikram sir, so that means rollback and commits are only meaningful for transactions. Am I right?

Answer 1

Answer D

Reason:-

You cannot rollback a DDL operation like ALTER TABLE because DDL is implicitly committed.

Comments

Perfect Explanation!

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BUT, can DML commands be rolled back?

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I think we can do rollback for DML.

Until a transaction is committed, it can be rolled back (undone)

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It really depends on the type of database you are using