If you know the x and y locations of each of the points it should be quite straightforward.
So, if your database has points 1 to 5 (for example) with x-locations x1 x2 x3 x4 x5 and similar for y, then you could say
X = [x1 x2 x3 x4 x5];
Y = [y1 y2 y3 y4 y5];
line(X,Y)
will plot a black line through those points
