MySQL测试通过

方法1. INSERT IGNORE INTO

insert ignore into actor values ('3', 'WD', 'GUINESS', '2006-02-15 12:34:33');

方法2. on duplicate key update；MySQL适用

insert into actor(actor_id, first_name, last_name, last_update)
values ('3', 'WD', 'GUINESS', '2006-02-15 12:34:33')
on duplicate key update first_name='WD', last_name='GUINESS', last_update='2006-02-15 12:34:33';

方法3. insert时带有where条件的写法；根据条件防止重复插入： INSERT INTO IF EXISTS

insert into actor(actor_id, first_name, last_name, last_update)
select 3, 'WD', 'GUINESS', '2006-02-15 12:34:33' from DUAL
where not exists (select actor_id FROM actor WHERE actor_id = 3);