DECLARE @Foo TABLE (CustName VARCHAR(50), ItemAssigned VARCHAR(50))

INSERT @Foo (CustName, ItemAssigned)
VALUES
('Joe Bloggs', 'Laptop'),
('Joe Bloggs', 'Monitor'),
('Joe Bloggs', 'Keyboard'),
('Bob Smith', 'Laptop'),
('Bob Smith', 'Monitor'),
('Bob Smith', 'Keyboard'),
('Sam Jones', 'Desktop'),
('Sam Jones', 'Monitor'),
('Sam Jones', 'Keyboard')

-- Get all DISTINCT Customers
SELECT DISTINCT CustName
FROM @Foo

-- Get all Users with laptops
SELECT CustName
FROM @Foo
WHERE ItemAssigned = 'LapTop'


-- Combine Queries
SELECT *
FROM
	(
		SELECT DISTINCT CustName
		FROM @Foo
	) AS Cust
LEFT OUTER JOIN
	(
		SELECT CustName
		FROM @Foo
		WHERE ItemAssigned = 'LapTop'
	) AS CustWithLaptops
	ON Cust.CustName = CustWithLaptops.CustName
WHERE
	CustWithLaptops.CustName IS NULL

SELECT [Cust Name]
FROM Table
GROUP BY [Cust Name]
HAVING SUM(CASE WHEN [Item assigned]='Laptop' THEN 1 ELSE 0 END) = 0