· 8 years ago · Jan 05, 2018, 01:40 PM
1CREATE TABLE IF NOT EXISTS test (
2 id int(11) NOT NULL,
3 reverse_id int(11) NOT NULL,
4 PRIMARY KEY (id),
5 UNIQUE KEY reverse_id (reverse_id)
6) ENGINE=InnoDB DEFAULT CHARSET=utf8;
7
8INSERT INTO test (id, reverse_id) VALUES ('1', '2'), ('2', '1');
9
10UPDATE test SET id = reverse_id;
11
12# Duplicate entry '2' for key 'PRIMARY'