批量插入数据：

insert into actor(actor_id,first_name,last_name,last_update)values(1,'PENELOPE','GUINESS','2006-02-15 12:34:33'),(2,'NICK','WAHLBERG','2006-02-15 12:34:33');

 

删除emp_no重复的记录，只保留最小的id对应的记录。

CREATE TABLE IF NOT EXISTS titles_test (

id int(11) not null primary key,

emp_no int(11) NOT NULL,

title varchar(50) NOT NULL,

from_date date NOT NULL,

to_date date DEFAULT NULL);

delete from  titles_test where id not in (    select min(id) from titles_test    group by emp_no)

 

sql 更新操作

update titles_testset  from_date = '2001-01-01',to_date = NULLwhere to_date = '9999-01-01'