Why are positional queries bad?

Question

I'm reading CJ Date's SQL and Relational Theory: How to Write Accurate SQL Code, and he makes the case that positional queries are bad — for example, this INSERT:

INSERT INTO t VALUES (1, 2, 3)

Instead, you should use attribute-based queries like this:

INSERT INTO t (one, two, three) VALUES (1, 2, 3)

Now, I understand that the first query is out of line with the relational model since tuples (rows) are unordered sets of attributes (columns). I'm having trouble understanding where the harm is in the first query. Can someone explain this to me?

Answer 1

The first query breaks pretty much any time the table schema changes. The second query accomodates any schema change that leaves its columns intact and doesn't add defaultless columns.

People who do SELECT * queries and then rely on positional notation for extracting the values they're concerned about are software maintenance supervillains for the same reason.