3 数据库常见函数

一、字符函数
length：获取参数值的字节个数
    例：select length('张三丰hahaha')  >> 一个中文字母占三个字节，一个英文字母占一个字节。
    
MySQL 5.0以上的版本：
1.一个汉字占多少长度与编码有关：
UTF－8：一个汉字＝3个字节
GBK：一个汉字＝2个字节
    
二、数学函数
三、日期函数
四、流程控制函数
五、分组函数

SELECT
(select top 1 name from sys_user_app where open_id = a.open_id and is_self = 1 ) as createName,
case when a.source_type = 1 then 'HIS系统' else '体检系统' end as sourceType,
a.create_date as createTime
FROM sys_user_app a
LEFT JOIN user_bind_record b ON b.id = a.record_id
${ew.customSqlSegment}

相关工作例子

SELECT
(select top 1 name from sys_user_app where open_id = a.open_id and is_self = 1 ) as createName,
case when a.source_type = 1 then 'HIS系统' else '体检系统' end as sourceType,
a.create_date as createTime,
stuff(b.telephone,5,4,'****') as telephone, 
b.age,
b.is_adult as isAdult, 
dd1.dict_label as cardType,
stuff(b.card_no,5,10,'****') as cardNo,
b.card_no as card_no_2,
stuff(b.address,10,15,'****') as address,
stuff(b.guard_card_no,5,10,'****') as guardCardNo
FROM sys_user_app a
LEFT JOIN user_bind_record b ON b.id = a.record_id
left join sys_dict_data dd on b.nation = dd.dict_value and dd.dict_type='2.16.156.10011.2.3.3.3'
left join sys_dict_data dd1 on dd1.dict_value = b.card_type and dd1.dict_type = 'card_type'
left join sys_dict_data dd2 on dd2.dict_value = b.guard_card_type and dd2.dict_type ='card_type'
${ew.customSqlSegment}

相关引用来源

https://blog.youkuaiyun.com/TiAmo_xixi/article/details/125909286