I claim the ornamental design for a table base, as shown and described.
FIG. 1 is a perspective view of a table base, showing my new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a bottom plan view thereof;
FIG. 4 is a right-side elevational view thereof;
FIG. 5 is a left-side elevational view thereof;
FIG. 6 is a front elevational view thereof; and,
FIG. 7 is a rear elevational view thereof.
The broken lines showing a table top in the figures, and elements on the bottom surface of the design in FIG. 3, depict environmental matter and form no part of the claimed design.