xml文件转义字符处理
（1）<![CDATA[ ]]>
（2）直接写转义后的字符
1、mysql里批量修改表内某个字段内的部分数据
UPDATE inventory_stock
SET batchno = REPLACE(batchno,\'-20-201901\',\'-50-2019\')
2、ON DUPLICATE KEY UPDATE
根据主键判断是新增还是修改（也可以有两个或多个主键）
INSERT INTO TABLE (a,c) VALUES (1,3) ON DUPLICATE KEY UPDATE c=c+1;
UPDATE TABLE SET c=c+1 WHERE a=1;
插入多条
<insert id="update" parameterType="com.ws.wsweb.entity.DingUser">
INSERT INTO ding_user (dinguserid, `name` ,openid,mobile) VALUES
<foreach collection="list" item="item" index="index" separator=",">
(#{item.dinguserid},#{item.name},#{item.openid},#{item.mobile})
</foreach>
ON DUPLICATE KEY UPDATE
`name` =values(name),openid=values(openid),mobile=values(mobile)
</insert>
INSERT INTO ding_user (dinguserid, `name` ,openid,mobile) VALUES
<foreach collection="list" item="item" index="index" separator=",">
(#{item.dinguserid},#{item.name},#{item.openid},#{item.mobile})
</foreach>
ON DUPLICATE KEY UPDATE
`name`=values(name),openid=values(openid)
1 insert into inventory_list 2 ( 3 listid,billid,billtypeid,invid,invtypeid,storeid,positionid 4 ,supplierid,productdate,validnum,batchno,count,memo,makerid 5 ) 6 values 7 <foreach collection="list" item="item" index="index" separator="," > 8 ( 9 uuid(),#{item.billid},#{item.billtypeid},#{item.invid},#{item.invtypeid},#{item.storeid},#{item.positionid} 10 ,#{item.supplierid},#{item.productdate},#{item.validnum},#{item.batchno},#{item.count},#{item.memo},#{item.makerid} 11 ) 12 </foreach>
3、 mysql插入一个字段
alter table task_list add chargeuserid varchar(50) DEFAULT NULL after userid;
UPDATE task_list SET chargeuserid =userid
AFTER userId : 必须加到最后
primary key ：若存在主键，语句会报错
// 插入一个字段和删除一个字段
alter table ding_attence ADD makedate datetime DEFAULT CURRENT_TIMESTAMP;
ALTER TABLE ding_attence DROP COLUMN maketime
ALTER TABLE ding_attence ADD `checkType` varchar(50) NOT NULL primary key DEFAULT \'OnDuty\' COMMENT \'考勤类型 OnDuty：上班；OffDuty：下班\' AFTER userId;
3.修改一个字段
alter table user MODIFY new1 VARCHAR(10); //修改一个字段的类型
alter table user CHANGE new1 new4 int;//修改一个字段的名称，此时一定要重新指定该字段的类型
4.id自动增加
`id` int(12) NOT NULL AUTO_INCREMENT
5.id重新恢复1
alter table ali.ali_product AUTO_INCREMENT=1;
//修改自增字段的初始值
ALTER TABLE base_purchare auto_increment=1
4、 REGEXP进行正则匹配
SELECT userid,username FROM sys_user AS a
INNER JOIN sys_department AS b ON a.depid = b.depid AND b.iused = 1
WHERE a.iused =1 AND b.depcode REGEXP CONCAT(\'^\',
(SELECT d.depcode FROM sys_user AS c
INNER JOIN sys_department AS d ON c.depid = d.depid WHERE c.userid = \'82200e23-5f1c-11e9-98bb-4ccc6a2f102e\')
)
5、insert 插入多条数据
INSERT INTO wx_user
SELECT userid ,\'\' AS openid FROM sys_user WHERE usercode = \'\'
6、查询表中一个字段是否有重复的值
SELECT invcode,
count(t1.invcode) AS ct
FROM
base_inventory AS t1
GROUP BY
t1.invcode
HAVING
ct > 1
6、修改（替换）表中某个字段的值
update table set name replace(name,\'name_\',\'\')
where name like \'name_%\';--替换
replace(name,\'name_\',\'\')
把name中出现\'name_\'的全部替换为\'\'
update table set name = substr(name,6) where name like \'name_%\'; --截取
mysql中的substr()函数
用法：
substr(string string,num start,num length);
string为字符串；
start为起始位置；
length为长度。
mysql中的start是从1开始的
substr(name,6) 从第六位开始到最后一位
update table set name= name +’内容’where id = 1
包含是否为空和NUL
UPDATE import_temp_invfile
SET state = 1 ,
errmsg = CONCAT(IF((ISNULL(errmsg) || LENGTH(trim(errmsg))<1),\'编码重复\',\'编码重复/\'),IFNULL(errmsg,\'\'))
WHERE invcode IN (1);
7、多个表的删除
DELETE m,p FROM ytd_meetings as m LEFT join ytd_meetingpic as p on m.meetingid = p.meetingid WHERE
m.meetingid in
<foreach item="item" collection="array" open="(" separator="," close=")">
#{item}
</foreach>
LETF JOIN 表示左侧表肯定删除，右侧有的话就删除
<foreach item="item" collection="array" open="(" separator="," close=")">
#{item}
</foreach>
collection="array" 类型
open="(" 开头
separator="," 分隔符
close=")" 结尾
8、表的插入（修改）
INSERT INTO ding_dep (id,name) VALUES
<foreach collection="list" item="item" index="index" separator=",">
(#{item.id},#{item.name})
</foreach>
ON DUPLICATE KEY UPDATE
name=values(name)
如果主键存在，做修改操作（只是修改name字段）
不存在做插入处理
9、转义字符的转换
对于一些 >、<等符号
<![CDATA[ ]]>
V-IF的使用
<if test="keyvalue != null and keyvalue != \'\'">
where name like concat(\'%\',#{keyvalue},\'%\')
</if>
10、时间戳的转换
1、13位时间戳转换为“yyyy-mm-dd hh:mm:ss”
FROM_UNIXTIME(round(b.start_time / 1000,0))
10位的则不用÷1000
2、“yyyy-mm-dd hh:mm:ss”转换为13位时间戳
SELECT (UNIX_TIMESTAMP(NOW())*1000)
--转换成10位的则不用*1000
SELECT UNIX_TIMESTAMP(\'2019-10-12 10:50:12\')
11、分组语句
根据时间查询 年-月-日
SELECT ROUND(AVG(b.temperaturevalue), 2) AS temVal , ROUND(AVG(b.humidityvalue), 2) AS humVal , DATE_FORMAT(b.makedate, \'%d\') AS day FROM sys_department a, msg_humitemp_record b WHERE (a.depid = b.depid AND a.depid = \'3b7ddcf4-87a9-4188-8a36-b97929dcd0ee\' AND year(b.makedate) = 2019 AND month(b.makedate) = 10) GROUP BY DATE_FORMAT(b.makedate, \'%Y-%m-%d\') ORDER BY b.makedate ASC
11、查询中加入一个选项
比查询完再加入相对简单
SELECT \'\' AS stateid, \'全部\' AS title UNION SELECT stateid, statename AS title FROM base_state WHERE statevalue = \'50\' ORDER BY stateid
12、Count()的三种用法
1、COUNT(a > b OR NULL)
2、SUM(if(a > b, 1, 0))
3、是2的实际写法（2为简写）
SUM(CASE
WHEN a > b THEN 1
ELSE 0
END)
SELECT DATE_FORMAT(visdate, \'%d\') AS title, COUNT(visid) AS totalcount , COUNT(temperature > maxtemperature OR NULL) AS effectcount , SUM(if(temperature > maxtemperature, 1, 0)) AS ss , SUM(CASE WHEN temperature > maxtemperature THEN 1 ELSE 0 END) AS aa FROM user_visitor WHERE DATE_FORMAT(visdate, \'%Y-%m\') = \'2020-02\' GROUP BY DATE_FORMAT(visdate, \'%d\') ORDER BY DATE_FORMAT(visdate, \'%d\') ASC;
parameterType="com.ws.wsweb.entity.DingUser"