CREATE   FUNCTION   f_Convert( 
    @str   NVARCHAR(4000),   --要轉換的字串 
    @flag   bit                             --轉換標誌,0轉換成半形,1轉換成全形 
)RETURNS   nvarchar(4000) 
AS 
BEGIN 
    DECLARE   @pat   nvarchar(8),@step   int,@i   int,@spc   int 
    IF   @flag=0 
        SELECT   @pat=N'%[！-～]%',@step=-65248, 
        @str=REPLACE(@str,N'　 ',N'   ') 
    ELSE 
        SELECT   @pat=N'%[!-~]%',@step=65248, 
        @str=REPLACE(@str,N'   ',N'　 ') 

    SET   @i=PATINDEX(@pat   COLLATE   LATIN1_GENERAL_BIN,@str) 
    WHILE   @i> 0 
        SELECT   @str=REPLACE(@str, 
        SUBSTRING(@str,@i,1), 
        NCHAR(UNICODE(SUBSTRING(@str,@i,1))+@step)) 
        ,@i=PATINDEX(@pat   COLLATE   LATIN1_GENERAL_BIN,@str) 
    RETURN(@str) 
END 
GO

呼叫：

 update table1 set column1=dbo.f_Convert(column1,0);

 declare @s1 varchar(8000) 
 select   @s1='中   　２-３４５６a７８ＳＴＵＶabｎ中國ｏｐｗｘｙｚ'
 select dbo.f_convert(@s1,0),dbo.f_convert(@s1,1)

https://www.cnblogs.com/karkash/p/6357510.html