What is MIXED-DML-OPERATION error and how to avoid?

Hi Prachi,

Mixed DML operations within a single transaction aren’t allowed. You can’t perform DML on a setup sObject and another sObject in the same transaction. However, you can perform one type of DML as part of an asynchronous job and the others in other asynchronous jobs or in the original transaction. This class contains an @future method to be called by the class in the subsequent example.

Use @future to Bypass the Mixed DML Error in a Test Method

public class InsertFutureUser {
@future
public static void insertUser() {
Profile p = [SELECT Id FROM Profile WHERE Name='Standard User'];
UserRole r = [SELECT Id FROM UserRole WHERE Name='COO'];
User futureUser = new User(firstname = 'Future', lastname = 'User',
alias = 'future', defaultgroupnotificationfrequency = 'N',
digestfrequency = 'N', email = 'test@test.org',
emailencodingkey = 'UTF-8', languagelocalekey='en_US',
localesidkey='en_US', profileid = p.Id,
timezonesidkey = 'America/Los_Angeles',
username = 'futureuser@test.org',
userpermissionsmarketinguser = false,
userpermissionsofflineuser = false, userroleid = r.Id);
insert(futureUser);
}
}

Hello,

Performing DML operation on more than two or two standard/custom object in the same transaction this error will come.

To avoid this error, we should perform DML operation on standard/custom object records in a different transaction.

Hope this will help you.

Thanks.