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The records in the book object are such, that one book can be the parent of other books, and it isn't necessary that each book has a parent book.

Given ID of a book, how to find out whether that book has child elements or not using an SOQL query?

Arjit Sharma
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1 Answers1

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In your example, Book__c custom object has a self-relationship. Let's say, the name of the field of this relation is ParentBook__c. You want to use the following SOQL in order to check if this Book__c record with Id ID_BOOK_TO_CHECK has any child:

SELECT Id, Name
FROM Book__c
WHERE ParentBook__c = ID_BOOK_TO_CHECK
LIMIT 2

If this SOQL query will return not empty List, that means this record is a parent. LIMIT 2 in this example, because LIMIT 1 returns a single record, and if no such record throws an exception.

Oleksandr Berehovskyi
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