mysql批量更新

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MySql中4种批量更新的方法
mysql 批量更新共有以下四种办法
1、.replace into 批量更新

replace into test_tbl (id,dr) values (1,'2'),(2,'3'),...(x,'y');
例子:

replace into book (

'Id',
'Author',
'CreatedTime',
'UpdatedTime'

) values (

1,
'张飞',
'2016-12-12 12:20',
'2016-12-12 12:20'

),(

2,
'关羽',
'2016-12-12 12:20',
'2016-12-12 12:20');

2、insert into ...on duplicate key update批量更新

insert into test_tbl (id,dr) values (1,'2'),(2,'3'),...(x,'y') on duplicate key update dr=values(dr);
例子:

insert into book
(Id,Author,CreatedTime,UpdatedTime)
values
(1,'张飞2','2017-12-12 12:20','2017-12-12 12:20'),
(2,'关羽2','2017-12-12 12:20','2017-12-12 12:20')
on duplicate key update
Author=values(Author),
CreatedTime=values(CreatedTime),
UpdatedTime=values(UpdatedTime);
replace into 和 insert into on duplicate key update的不同在于:

replace into 操作本质是对重复的记录先delete 后insert,如果更新的字段不全会将缺失的字段置为缺省值,用这个要悠着点否则不小心清空大量数据可不是闹着玩的。
insert into 则是只update重复记录,不会改变其它字段。
3.创建临时表,先更新临时表,然后从临时表中update

create temporary table tmp(id int(4) primary key,dr varchar(50));
insert into tmp values (0,'gone'), (1,'xx'),...(m,'yy');
update test_tbl, tmp set test_tbl.dr=tmp.dr where test_tbl.id=tmp.id;
注意:这种方法需要用户有temporary 表的create 权限。

4、使用mysql 自带的语句构建批量更新

mysql 实现批量 可以用点小技巧来实现:

UPDATE yoiurtable
SET dingdan = CASE id

WHEN 1 THEN 3 
WHEN 2 THEN 4 
WHEN 3 THEN 5 

END
WHERE id IN (1,2,3)
这句sql 的意思是,更新dingdan 字段,如果id=1 则dingdan 的值为3,如果id=2 则dingdan 的值为4……
where部分不影响代码的执行,但是会提高sql执行的效率。确保sql语句仅执行需要修改的行数,这里只有3条数据进行更新,而where子句确保只有3行数据执行。
例子:

UPDATE book
SET Author = CASE id

WHEN 1 THEN '黄飞鸿' 
WHEN 2 THEN '方世玉'
WHEN 3 THEN '洪熙官'

END
WHERE id IN (1,2,3)
如果更新多个值的话,只需要稍加修改:

UPDATE categories
SET dingdan = CASE id

WHEN 1 THEN 3 
WHEN 2 THEN 4 
WHEN 3 THEN 5 

END,
title = CASE id

WHEN 1 THEN 'New Title 1'
WHEN 2 THEN 'New Title 2'
WHEN 3 THEN 'New Title 3'

END
WHERE id IN (1,2,3)
例子:

UPDATE book
SET Author = CASE id

WHEN 1 THEN '黄飞鸿2' 
WHEN 2 THEN '方世玉2'
WHEN 3 THEN '洪熙官2'

END,
Code = CASE id

WHEN 1 THEN 'HFH2' 
WHEN 2 THEN 'FSY2'
WHEN 3 THEN 'HXG2'

END
WHERE id IN (1,2,3)
具体的MyBatis代码如下:

<update id="update" parameterType="java.util.List">

UPDATE dic_col_display
SET column_code = CASE id
<foreach collection="list" item="item" index="index" open="" separator="" close="">
    WHEN #{item.id} THEN #{item.column_code} 
</foreach>
END,
column_desc = CASE id
<foreach collection="list" item="item" index="index" open="" separator="" close="">
    WHEN #{item.id} THEN #{item.column_desc} 
</foreach>
END,
modify_user_id = CASE id
<foreach collection="list" item="item" index="index" open="" separator="" close="">
    WHEN #{item.id} THEN #{item.modify_user_id} 
</foreach>
END,
modify_user_name = CASE id
<foreach collection="list" item="item" index="index" open="" separator="" close="">
    WHEN #{item.id} THEN #{item.modify_user_name} 
</foreach>
END,
modify_date = NOW()
WHERE
  id in
  <foreach collection="list" item="item" index="index" open="(" separator="," close=")">
      #{item.id} 
  </foreach>

</update>

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