Exclusive LEFT OUTER JOIN
An exclusive LEFT OUTER JOIN can be used to check for the presence of data in one table that is absent in another table. To create an exclusive LEFT OUTER JOIN the right query requires an IS NULL filter condition on the joining column.
Your sales manager is concerned that orders from French customers are declining. He wants you to compile a list of French customers that have not placed any orders so he can contact them.
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Improving Query Performance in SQL Server
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-- First attempt
SELECT c.CustomerID,
c.CompanyName,
c.ContactName,
c.ContactTitle,
c.Phone
FROM Customers c
___ ___ ___ Orders o -- Joining operator
ON c.___ = o.___ -- Joining columns
WHERE c.Country = 'France';