declare @dDate datetime
select @dDate =null
print @ddate
if @dDate is null select @dDate ='2004-1-1'
print @dDate --测试:
01 1 2004 12:00AM
select @dDate =null
print @ddate
if @dDate is null select @dDate ='2004-1-1'
print @dDate --测试:
01 1 2004 12:00AM
declare @dDate datetime
select @dDate =''
if isdate(@dDate)=0 select @dDate ='2004-1-1'
print @dDate
结果:
Jan 1 1900 12:00AM
declare @dDate varchar(10)
select @dDate =''
if len(@dDate)=0 select @dDate ='2004-1-1'
print @dDate --返回 2004-1-1
declare @dDate datetime
select @dDate =null
if @dDate is null select @dDate ='2004-1-1'
print convert(varchar(10),@dDate ,120)
--返回 2004-1-1