The reason for atomicity is pretty standard here..one of my records fails to save, if an error occurs, I want to ensure that everything I attempted will roll back, preventing data from being out of sync.When you set this to false, what that means is that if one record has an exception, validation rule failure (which actually is just a thrown exception), Trigger validation failure ( validation rules.
And then, I have an after Update trigger and that's at this moment I see the validation rules error in the log. So I think the update works well but i don't know why I can't do some stuff after it ! If something fails, then make the entire transation fail.Formally, a "database" refers to a set of related data and the way it is organized.Access to this data is usually provided by a "database management system" (DBMS) consisting of an integrated set of computer software that allows users to interact with one or more databases and provides access to all of the data contained in the database (although restrictions may exist that limit access to particular data).It is a way to prevent one validation rule failure from causing many good records from failing.To get your save to work, you need to understand what your validation rule failure is, and then attempt to save data that meets the validation criteria that have been set in your system.Salesforce allows you to perform database transactions (insert, update, delete, etc.) using either DML statments or DML database methods.