SQLite

The DELETE statement on the third line of the example below only deletes a
single row, rather than two rows as expected.  The correct behavior, confirmed by running on PostgreSQL, is to delete two rows, such that the final answer is a single row with value "1".

<blockquote><verbatim>
CREATE TABLE t1(x INT);
INSERT INTO t1 VALUES(1),(2),(3);
DELETE FROM t1 WHERE EXISTS(SELECT 1 FROM t1 AS v WHERE v.x=t1.x-1);
SELECT * FROM t1;
</verbatim></blockquote>

Bisecting shows that this problem results from the one-pass optimization
at check-in [8b93cc59370].  The problem was reported on the sqlite-users
mailing list by Rob Golsteijn.

Versions affected by this bug: 3.9.0 through 3.12.2.