sqlserver常用函数笔记

根据原文做的笔记·

add--

--CONVERT() + CAST()
DECLARE @int int =5 
print  '@int Convert to varchar ...' + CONVERT(varchar(100),@int)
print '@int Cast to varchar ...' + cast(@int as varchar(100))

add--

--DATEADD ( datepart,number,date ) 
DECLARE @DateTest DATETIME2 = '2013-01-01 1:1:1.1234567'
select 'Year',DATEADD ( year,1,@DateTest ) 
Union All
Select 'Quarter',DATEADD (QUARTER,@DateTest) --Her PinYin Is JiDu
Union All
Select 'Month',DATEADD(MONTH,@DateTest)
Union All
Select 'Week',DATEADD(WEEK,@DateTest)
Union All
Select 'DAYOFYEAR',DATEADD(DAYOFYEAR,@DateTest)
Union All
Select 'WeiMiao',DATEADD(MICROSECOND,@DateTest)
Union All
Select 'HaoMiao',DATEADD(MILLISECOND,@DateTest)


--DATEDIFF ( datepart,startdate,enddate ) 
Select 'HaoMiao',DATEDIFF(MILLISECOND,'2000-1-1 1:1:1.111','2000-1-1 1:1:1.112')
Union All
Select 'WeiMiao',DATEDIFF(MICROSECOND,'2000-1-1 1:1:1.123456','2000-1-1 1:1:1.123457')
Union All
Select 'XiaoShi',DATEDIFF(HOUR,'2000-1-1 2:1:1.123456')


--DATENAME ( datepart,date )
Select 'Year',DATENAME(YEAR,'2000-1-1 1:1:1.123456')
Union All
Select 'Hour',DATENAME(HOUR,'2000-1-1 1:1:1.123456')


--DATEPART ( datepart,date ) 
SELECT 'YEAR',DATEPART(YEAR,'2000-1-1 1:1:1.123456')
Union All
Select 'HaoMiao',DATEPART(MILLISECOND,'2000-1-1 1:1:1.123456')


--DAY ( date ) + MONTH ( date ) + YEAR ( date )
DECLARE @DAY DATETIME2 = '2000-1-10 1:1:1.1234567'
Select 'DAY',DAY(@DAY)
Union All
Select 'Month',MONTH(@DAY)
Union All
Select 'Year',YEAR(@DAY)


--GETDATE ( )
Select 'Now',GETDATE()

--LOWER( ) + UPPER( ) 
DECLARE @DaXiaoXie varchar(100) = 'AaBbCcDd'
Select 'XiaoXie',LOWER(@DaXiaoXie)  
Union All
Select 'DaXie',UPPER(@DaXiaoXie)

--LTRIM()
Select 'DelThisQianKongGe',LTRIM('   This') 

--SUBSTRING()
Select 'SUBSTRING',SUBSTRING('123456',2,3)--Result __ SUBSTRING 234


--ROUND
Select 'Round',ROUND(748.58,-2) --Result __ Round_700.00
Union All
Select 'Round',-1) --Result __ Round_750.00
Union All
Select 'Round',0)  --Result __ Round_749.00
Union All
Select 'Round',1)  --Result __ Round_748.60
Union All
Select 'Round',2)  --Result __ Round_748.58

--FLOOR( ) 
Select 'Floor',FLOOR(123.45),FLOOR(-123.45),FLOOR($123.45) --Result __ Floor__123__-124__123.00

--CEILING()
Select 'CEILING',CEILING(123.45) --Result __ CEILING__124

--DATALENGTH()
Select 'DATALENGTH',DATALENGTH('Zhang')  --Result __ DATALENGTH__5