一、字符串函数
#concat
Select concat ('hello','world');
#lower
Select lower ('HELLO');
#upper
Select upper ('hello');
#lpad
Select lpad ('wang',8,'--');
#trim
Select trim('helloworld');
二、数值函数
#ceil
Select ceil(1.1);
#floor
Select floor(1.8);
#rand
Select rand();
#mod
Select mod(3,4);
#round
Select round(3.33332222,4);
三、日期函数
#curdate
Select curdate();
#curtime
Select curtime();
#now
Select now();
#year
Select year(now());
#month
Select month(now());
#day
Select day(now());
#date_add(date,intervalexprtype)
Select date_add (now(),interval 70 year);
#datediff(date1,date2)
Select datediff ('2023-01-30','2021-08-01');
四、流程函数
Select if (true,1,2);
Select if null ('ok','false');
Select if null(null,'false');
Select name,(case workaddress when '北京' then '一线城市' when '上海' then '一线城市' else '二线城市' end) as '工作地址' from user;
