SQLite

See forum post from Vladimir Panteleev here: https://sqlite.org/forum/forumpost/96896f825d

Reproduce with:

    CREATE TABLE t1(a INTEGER PRIMARY KEY, b, c)
    WITH s(i) AS (
      SELECT 1 UNION ALL SELECT i+1 FROM s WHERE i<50000
    )
    INSERT INTO t1(a, b, c) SELECT i, 123, 456 FROM s;
    ALTER TABLE t1 DROP COLUMN b;

    SELECT count(*), c FROM t1 GROUP BY c;

The result of the final query should be (50000, 456) - the value of "c" for all rows is 456 - but instead shows that for some rows "c" has the value 123.