Tampilan SQL:Bergabung dengan tabel tanpa menyebabkan data terduplikasi di setiap baris?

Anda harus menggunakan UNION (sebenarnya UNION ALL) dalam kasus ini.

select a.name as account_Name, 
       p.description as property_DESCRIPTION, 
       p.address as property_ADDRESS, 
       null as vehicles_DESCRIPTION,
       null as vehicles_MAKE, 
       null as vehicles_MODEL
    from Accounts a
        inner join Properties p
            on a.accountid = p.accountid
UNION ALL   
select a.name as account_Name, 
       null as property_DESCRIPTION, 
       null as property_ADDRESS, 
       v.description as vehicles_DESCRIPTION,
       v.make as vehicles_MAKE, 
       v.model as vehicles_MODEL
    from Accounts a
        inner join vehicles v
            on a.accountid = v.accountid