It's interesting you did not point out the possibility of a "double unknown" of using this method. That is, it's possible for the error field to be either 0 or NULL. Both values would have, essentially, the same meaning. It's possible to make use of this fact, say 0 is success and NULL is the program has reported back yet.

But, I would really love to know more, specifically, how large your dictionary can be? This is complicated by the fact that MS stores your larger values signed. For example, a TINYINT is unsigned and can store 7 concurrent values in addition to NULL and 0. But in order to expand beyond that using SMALLINT, you have to divide the value between positive and negative, -2^15 (-32,768) to 2^15-1 (32,767). This gives you 14 concurrent values on the positive side (with 0) and 15 on the negative (without). If SMALLINT were unsigned, you would have 15 with 0 and NULL. INT gives you 30, and BIGINT gives you 62. Essentially, that means that this is only a viable alternative if you need to assign fewer than 62 matches. Or, perhaps the NUMERIC data type can be used for bigger numbers?