Here's one way. The expected indexes are essential.

DECLARE @Emp TABLE

(

Empid INT PRIMARY KEY CLUSTERED,

EmpName VARCHAR(10)

)

DECLARE @Proj TABLE

(

ProjID INT PRIMARY KEY CLUSTERED,

ProjName VARCHAR(10)

)

DECLARE @EmpProj TABLE

(

EmpID INT,

ProjID INT,

PRIMARY KEY CLUSTERED (EmpID, ProjID)

)

INSERT INTO @Emp SELECT 1, 'Tony' UNION ALL SELECT 2,'Romo'

INSERT INTO @Proj SELECT 1, 'Project 1' UNION ALL SELECT 2, 'Project 2'

INSERT INTO @EmpProj SELECT 1, 1 UNION ALL SELECT 2, 1 UNION ALL SELECT 2, 2

;

WITH

cte AS

( --=== Find employees NOT in a project

SELECT e.EmpID, p.ProjID FROM @Emp e CROSS JOIN @Proj p

EXCEPT

SELECT EmpID, ProjID FROM @EmpProj

) --=== Find employess NOT in the list above

SELECT *

FROM @Emp

WHERE EmpID NOT IN (SELECT EmpID FROM CTE)

;