巧妙的Sql函數日期處理方法

/*本月第一天日期*/
SELECT FirstDayOfCurrentMonth = dateadd(mm,datediff(mm,0,getdate()),0)
SELECT FirstDayOfCurrentMonth = convert(CHAR(8),getdate(),120)+'1'
/*下月第一天日期*/
SELECT FirstDayOfNextMonth = dateadd(mm,datediff(mm,0,getdate())+1,0)
/*本月最後一天日期*/
SELECT LastDayOfCurrentMonth = dateadd(dd,-1,dateadd(mm,datediff(mm,0,getdate())+1,0))
SELECT LastDayOfCurrentMonth = dateadd(dd,-1,convert(DATETIME,convert(CHAR(8),dateadd(mm,1,getdate()),120)+'1'))
/*本月天數*/
SELECT NumberOfDaysOfCurrentMonth =
 convert(INT,
 dateadd(mm,datediff(mm,0,getdate())+1,0)
 -
 dateadd(mm,datediff(mm,0,getdate()),0))

SELECT NumberOfDaysOfCurrentMonth = day(dateadd(day,-1,convert(CHAR(8),dateadd(month,1,getdate()),120)+'1'))