CREATE database Func
use Func
drop table 
create table user
(
	UID int PRIMARY key auto_increment,
	UNameID int UNIQUE,
	UName VARCHAR(25) ,
	UCode VARCHAR(25) ,
	UCost DECIMAL not null,
	UCState VARCHAR(25) not null,
	Uptime datetime not null, 
	Uamend datetime not NULL
)
create table depot
(
	DID int PRIMARY key auto_increment,
	UNameID int UNIQUE,
	Dquantity int not null,
	FOREIGN key (UNameID) REFERENCES user(UNameID)
)

select ABS(UCost) from user

select CEIL(888.55)

select ceiling(888.22)

select FLOOR(55.22)

select RAND(5)

select ROUND(555.55)

select ROUND(555.34)

SELECT LENGTH('555555')

select CHAR_LENGTH('665222')

select REPLACE('54321',1,0)

SELECT INSERT('987654321',3,2,'2')

SELECT LEFT('987654321',1)

SELECT RIGHT('987654321',1)

select SUBSTRING('987654321',2,3)

select CONCAT('987654321','asd')

select LOWER('ASD')

select UPPER('asd')

select REVERSE('123456789')

SELECT TRIM('   sdf ')

SELECT LTRIM('   sdf ')

SELECT RTRIM('   sdf ')

SELECT REPLACE('   sd  f ',' ','')

SELECT NOW()


SELECT FROM_UNIXTIME('10086'),UNIX_TIMESTAMP('2021-09-02 16:44:09')

SELECT IF(UCost>1000,'土豪','土狗') from user

SELECT CASE UCState
	WHEN 1 THEN
		'在线'
	WHEN 2 THEN
		'离线'
	ELSE
		'未知状态'
END 
 from user
 
SELECT IFNULL(UCost,'0') from user