Index[SYMBOL] [A] [B] [C] [D] [E] [F] [G] [H] [I] [J] [K] [L] [M] [N] [O] [P] [Q] [R] [S] [T] [U] [V] [W] [Y] [Z] keys alternate keys artificial versus natural keys 2nd artificial keys artificial primary keys 2nd 3rd as representative fields candidate keys 2nd natural keys versus artificial keys 2nd primary keys 2nd 3rd 4th 5th 6th 7th 8th exclusive identification 2nd gaps in 2nd 3rd three-field primary keys 2nd qualities of 2nd searching for 2nd 3rd 4th |