SQL全角半角互换

create function F_Convert(
@str nvarchar(4000), --
@flag bit            --0转化成半角；1转化成全角
)returns nvarchar(4000)
as
begin
declare @pat nvarchar(8),@step int,@i int,@spc int
if @flag=0
select @pat=N'%[！-～　]%',@step=-65248
else
select @pat=N'%[!-~ ]%',@step=65248
set @i=patindex(@pat COLLATE Latin1_General_BIN,@str)
while @i>0
select @str=stuff(@str,@i,1,nchar(case unicode(substring(@str,@i,1))
when 32 then 12288
when 12288 then 32
else unicode(substring(@str,@i,1))+@step end))
,@i=patindex(@pat COLLATE Latin1_General_BIN,@str)
return(@str)
end