What Is DML?

Account acc = new Account(Name = 'Acme Logistics');
// At this point, acc only exists in memory — nothing is saved yet.

insert acc;
// Now acc is a real, permanent row in the Account table.

1. Account acc = new Account(Name = 'Acme Logistics'); — every sObject you've created so far in this course — back to Module 18's new Account() — only exists in memory at this point.
2. // At this point, acc only exists in memory — nothing is saved yet. — spells it out.
3. (blank line)
4. insert acc; — DML (Data Manipulation Language) is what actually writes a change to the real Salesforce database.
5. // Now acc is a real, permanent row in the Account table. — permanent and visible to every other part of the org.

insert acc;  // create a brand-new record
update acc;  // change an existing record
delete acc;  // remove an existing record
upsert acc;  // insert if new, update if it already exists

1. insert acc; — creates a brand-new record.
2. update acc; — changes an existing record.
3. delete acc; — removes an existing record.
4. upsert acc; — inserts if new, updates if it already exists.

Each of the next several lessons goes deep on one of these — this lesson is the map of the territory, not the full detail on any one statement yet.