What is Database.rollback in Salesforce?

Hello Shariq,

Before You Started With Database.rollback  you must knew about Database.savepoint .

Database.savepoint :

database.savepoint is a method which is used to define a point which can be roll back to. If any error occurs during a transaction, that contains many statements, the application will roll back to the most recent savepoint and the entire transaction will not be aborted. Any DML statement that occurs after the savepoint can be discarded, and the database can be restored to the same condition it was in at the time you generated the savepoint.

you can refer to the following code:

Account a = new Account(Name = 'xxx'); insert a;
System.assertEquals(null, [SELECT AccountNumber FROM Account WHERE Id = :a.Id].
AccountNumber);

// Create a savepoint while AccountNumber is null
Savepoint sp = Database.setSavepoint();

// Change the account number
a.AccountNumber = '123';
update a;
System.assertEquals('123', [SELECT AccountNumber FROM Account WHERE Id = :a.Id].
AccountNumber);

// Rollback to the previous null value
Database.rollback(sp);
System.assertEquals(null, [SELECT AccountNumber FROM Account WHERE Id = :a.Id].
AccountNumber);