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1sql: change primary key to another list of unique elements
2CREATE TABLE IF NOT EXISTS test (
3  id int(11) NOT NULL,
4  reverse_id int(11) NOT NULL,
5  PRIMARY KEY (id),
6  UNIQUE KEY reverse_id (reverse_id)
7) ENGINE=InnoDB DEFAULT CHARSET=utf8;
8
9INSERT INTO  test (id, reverse_id) VALUES ('1',  '2'), ('2',  '1');
10
11UPDATE test SET id = reverse_id;
12
13# Duplicate entry '2' for key 'PRIMARY'