Query Language(cont) Domain calculus: x,x2,,X, F(x x2, ,x,) where x, is a domain variable, and Fx, x,, x, )is a well formed formula Example Lx, y EMP(x, y, Manager")) Variables are position sensitive6 Domain calculus: where xi is a domain variable, and is a well formed formula Example: { x, y | EMP(x, y, “Manager") } x1 , x2 ,  , xn | F(x1 , x2 ,  , xn ) ( ) n F x , x , , x 1 2  Variables are position sensitive! Query Language (cont.)