SOQL Query Where Id "In" Versus "Equals"(=)

Question

I just stumbled upon a soql query where somebody did the following

List<String> names = new List<String>{'John', 'Moe', 'Jeanette', 'Tony'};

List<Client__c> clients = [
    SELECT Id
    FROM Client__c
    WHERE First_Name__c = :names
];

I am not familiar with the usage of the equal sign(=) to check against a list/set as opposed to WHERE First_Name__c IN :names.

I am having a hard time finding the difference as it seems like using = works similarly but does it work the same way? Are there any dangers to using it?

Answer 1

I've not seen a difference functionally; I strongly prefer using IN as that is what would be required in SQL, and it is more accurate, and more descriptive.

First_Name__c is not logically equal to a list.

Using the syntax First_Name___c IN :names makes it clear that names is a collection, and that the developer knows that it's a collection

Answer 2

They are functionally equivalent. I agree with Mike that IN is more syntactically clear, but either one works.

See also: How to find out if an Object is a collection or single value?

This equivalence can be quite useful when building dynamic SOQL.