Salesforce 面试题与答案
问题 36. Explain the difference between a before trigger and an after trigger in Salesforce.
A before trigger in Salesforce runs before the record is saved to the database, allowing developers to modify the record before it is committed. An after trigger runs after the record is saved, enabling actions based on the final state of the record.
问题 37. What is the purpose of the 'Database.Stateful' interface in Apex?
The 'Database.Stateful' interface in Apex is used to maintain the state of variables between different invocations of a batch Apex job. It allows variables to retain their values throughout the execution of the batch.
问题 38. Explain the use of the 'WITH SECURITY_ENFORCED' clause in SOQL queries.
The 'WITH SECURITY_ENFORCED' clause in SOQL queries is used to enforce field- and object-level security in Apex code. It ensures that queries respect the current user's permissions and visibility.
问题 39. What is the purpose of the 'Test.startTest()' and 'Test.stopTest()' methods in Apex testing?
'Test.startTest()' and 'Test.stopTest()' methods in Apex testing are used to separate the execution context for the part of the code that precedes 'startTest()' and the part that follows 'stopTest()'. This is helpful for testing asynchronous code and resetting governor limits.
问题 40. Explain the concept of an external ID in Salesforce.
An external ID in Salesforce is a custom field that is used to match records in Salesforce with records in an external system. It allows for the integration and synchronization of data between Salesforce and external systems.
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