SQL 常用函数

--时间函数:
SELECT DATEADD(YEAR,10,GETDATE())
select DATEDIFF(year,getdate(),getdate())
SELECT DATENAME(month,GETDATE())
SELECT DATEPART(MONTH,GETDATE())
SELECT DAY(GETDATE())
SELECT GETDATE()
SELECT GETUTCDATE()
SELECT MONTH(GETDATE())
SELECT YEAR(GETDATE())

--数学运算函数：
SELECT ABS(CONVERT(INT,-123548545))
SELECT FLOOR(1.12)
SELECT CEILING(1.12)
SELECT PI()
SELECT POWER(100,-1)
SELECT RAND(0.12)
SELECT ROUND(1.254,1)

--字符串函数:    
SELECT ASCII('A')
SELECT CHAR(65)
SELECT CHARINDEX('ik','MIKE')
SELECT LEFT('MIKE',2)
SELECT LEN('MIKE ')
SELECT LOWER('miKE')
SELECT LTRIM(' MIKE')
SELECT NCHAR('97')
SELECT PATINDEX('%CH%','mikechang')
SELECT REPLACE('MIKECHANG','ch','SPRIT')
SELECT len(REPLICATE('mi',10))
SELECT REVERSE('mikesoft')
SELECT RIGHT('MIKESOFT',3)
SELECT RTRIM('MIKESOFT ')
SELECT LEN(SPACE(10))
SELECT STR(123.215,1,2)
SELECT STUFF('mikechang',2,3,'sprite')
SELECT SUBSTRING('mikechang',2,3)
SELECT UNICODE('KE')
SELECT UPPER('mike')

--系统函数
SELECT APP_NAME()
SELECT COALESCE(NULL,NULL,100)
SELECT CURRENT_USER
SELECT DATALENGTH(' MIKEC ')
SELECT @@ERROR
SELECT HOST_ID()
SELECT HOST_NAME()
SELECT @@IDENTITY
SELECT NEWID()
SELECT ISDATE('20132')