SQLite

In the following SQL, the first query returns no rows whereas the second query returns one row. Both queries should operate as the second.

CREATE TABLE t1(x TEXT UNIQUE COLLATE nocase);
INSERT INTO t1(x) VALUES(x'616263');
SELECT 'query-1', x FROM t1 WHERE x LIKE 'a%';
SELECT 'query-2', x FROM t1 WHERE +x LIKE 'a%';

This problem appears to have been introduced on 2005-08-28 (9.5 years ago) by check-in [ef84ff795c85e9d2]. And yet the problem has never been observed in the wild. The problem was discovered by the SQLite developers while reasoning about the validity of the LIKE optimization.