Mysql相关

触发器：

触发器只能作用在表的增删改操作上

新增时触发器

begin 
 insert into txf_alterinfo
  (uqalterid, alterbef, alterafter, uqfieldid, uqentityid, uquserid, operatedate, uqkeyid, varmemo)
values
  (uuid(), '', new.varname, 'UQPROJECTID', 'TXF_PROJECT', new.create_user, NOW(), new.uqprojectid, '项目新增');

	insert into txf_project_rensume
			(id, uqprojectid, vartype, resume, altertime, create_time, create_user, update_time, update_user, `desc`)
	values
			(uuid(), new.uqprojectid,1, '项目初始录入',date_format(now(), '%Y-%m-%d'), NOW(),new.create_user, 
			NULL,NULL,'项目初始录入');
end

修改时触发器

begin 
	DECLARE oldvalue VARCHAR(1000);
	DECLARE newvalue VARCHAR(1000);
  DECLARE user_name VARCHAR(50) DEFAULT '';
	IF(new.projectstate='20_2') then     -- 双重if   结尾必须要有end if结束
	if(IFNULL(new.varname,'') != IFNULL(old.varname,'')) then
		insert into txf_alterinfo
			(uqalterid, alterbef, alterafter, uqfieldid, uqentityid, uquserid, operatedate, uqkeyid, varmemo)
		values
			(uuid(), old.varname, new.varname, 'VARNAME', 'TXF_PROJECT', new.update_user, NOW(), NEW.uqprojectid, '项目名称变更');
			
		insert into txf_project_rensume
				(id, uqprojectid, vartype, resume, altertime, create_time, create_user, update_time, update_user, `desc`)
		values
				(uuid(), new.uqprojectid,8, CONCAT('项目名称变更为：', new.varname),date_format(now(), '%Y-%m-%d'), NOW(),old.create_user,  NOW(),NEW.update_user,CONCAT( old.varname,'项目名称变更为：', new.varname));  
	end if;
	end if;
end

mysql定义变量 与 变量赋值

DECLARE oldvalue VARCHAR(1000); -- 定义变量
	DECLARE newvalue VARCHAR(1000);
	SELECT a.dict_label INTO newvalue FROM sys_dict_data a WHERE dict_type='org_resume' and dict_value=1;	-- 变量赋值

mysql拼接字符串 参数

CONCAT( oldvalue,"法人名称变更为：",newvalue)

mysql切割“,”字符串

SELECT substring_index(substring_index('1_1,1_2', ',', b.help_topic_id + 1), ',', -1) dictvalue
		FROM mysql.help_topic b

mysql日期类型转换

select date_format(now(), '%Y-%m-%d') FROM dual

字符串数字排序

order by lpad(a.varno,5,'0') asc

mysql多字段模糊查询一个参数

select * from txf_project where CONCAT(`cyry`,`projectmanager`,`TECMANAGER`) like concat('%', '5db05328-bf94-4795-bb31-a4f4cd373b40', '%')

mysql字符串逗号分隔（行变列）

SELECT 
				SUBSTRING_INDEX(SUBSTRING_INDEX((select servicecontent from txf_project) AS num 
		FROM 
				mysql.help_topic 
		WHERE 
				help_topic_id < LENGTH((select servicecontent from txf_project))-
				LENGTH(REPLACE((select servicecontent from txf_project ),',',''))+1

mysql子查询 FIND_IN_SET

select a.* from sys_dict_data a where  FIND_IN_SET(a.dict_value,'6_7,6_6,6_5,6_4')

mysql逗号转换（字符转换）

-- 先转换 后拼接成想要的字符   但是不可用子查询 in   
select servicecontent, (CONCAT("'",replace(servicecontent,',',"','"),"'")) FROM txf_project

备份一张表&&修改表明

create table txf_file20210118 as select * from txf_file20210117
  ALTER TABLE TXF_FILE20210117 RENAME TO TXF_FILE

[Mysql中将查询出来的多列的值用逗号拼接] (列变行) 逗号分隔

select  group_concat(字段名) from 表名

Mysql 替换某个字段中的某个字符

update txf_filemap set  FILEPATH = REPLACE (FILEPATH,'c:','C:')

mysql时间戳转换

-- 时间戳 2018-08-09
SELECT CURDATE();
-- 2018-08-09 11:16:03
SELECT now();
-- 1618219395
select unix_timestamp(now())+10000;
-- 1533744000
select unix_timestamp(CURDATE());

select from_unixtime(unix_timestamp(now())+500, '%Y-%m-%d %H:%i:%s')

数据迁移(复制)

MySQL将一张表的某些列数据，复制到另外一张表

INSERT INTO t_topic_content(content,topicId) SELECT content,id FROM t_topic;

注意：给某一列数据赋值，自增长，那么就不应该插入数据了

MySQL将一张表的某些列数据，复制到另外一张表，并且修改某些内容。方法同上， 只是查询的时候使用REPLACE(str,from_str,to_str) 函数

INSERT INTO t_topic_content(content,topicId)
  SELECT REPLACE(content, 'aa', 'bb'),id FROM t_topic

MySQL分页插件 PageHelper自定义Count查询

<select id="selectLeftjoin" resultType="com.github.pagehelper.model.User">
    select a.id,b.name,a.py from user a
    left join user b on a.id = b.id
    order by a.id
</select>
<select id="selectLeftjoin_COUNT" resultType="Long">
    select count(distinct a.id) from user a
    left join user b on a.id = b.id
</select>

mysql 只满足一个条件的 in 查询 避免扫描全表

原理：前面为主表 只需要把 in 后面的sql 换成下方字段即可

not exists (select 1 from txf_zhiye_tuisong_log tl where tl.zhiyetimeid = a.id)

mysql替换字符集

ALTER TABLE txf_homepageinfo convert to CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;

mysql一对多查询最新一条数据

查询最近的一条执业反馈单

select  * from  txf_zhiye where create_time  in (select  MAX(create_time) from  txf_zhiye GROUP BY uqprojectid) and  zhiyetype=1