A relational database D is given with Ω as the set of attributes. The rows (tuples, data of one individual) are transmitted through a noisy channel. It is supposed that at most one data in a row can be changed by the transmission. We say that A → b (A ⊂ Ω, b ∈ Ω) is an error-correcting functional dependency if the data in A uniquely determine the data in b in spite of the error. We investigate the problem how much larger a minimal error-correcting functional dependency can be than the original one.