SQL SERVER 得到漢字首字母函數四版全集 –【葉子】

--建立取漢字首字母函數(第三版)create function [dbo].[f_getpy_V3] (@col varchar(1000))returns varchar(1000)as     begin        declare @cyc int,@len int,@sql varchar(1000),@char varbinary(20)        select @cyc = 1,@len = len(@col),@sql = ''        while @cyc <= @len             begin                  select @char = cast(substring(@col, @cyc, 1) as varbinary)declare @maco table (bcode varbinary(20),ecode varbinary(20),letter varchar(10))insert into @macoselect 0XB0A1,0XB0C4,'A' union allselect 0XB0C5,0XB2C0,'B' union allselect 0XB2C1,0XB4ED,'C' union allselect 0XB4EE,0XB6E9,'D' union allselect 0XB6EA,0XB7A1,'E' union allselect 0XB7A2,0XB8C0,'F' union allselect 0XB8C1,0XB9FD,'G' union allselect 0XB9FE,0XBBF6,'H' union allselect 0XBBF7,0XBFA5,'J' union allselect 0XBFA6,0XC0AB,'K' union allselect 0XC0AC,0XC2E7,'L' union allselect 0XC2E8,0XC4C2,'M' union allselect 0XC4C3,0XC5B5,'N' union allselect 0XC5B6,0XC5BD,'O' union allselect 0XC5BE,0XC6D9,'P' union allselect 0XC6DA,0XC8BA,'Q' union allselect 0XC8BB,0XC8F5,'R' union allselect 0XC8F6,0XCBF9,'S' union allselect 0XCBFA,0XCDD9,'T' union allselect 0XCDDA,0XCEF3,'W' union allselect 0XCEF4,0XD1B8,'X' union allselect 0XD1B9,0XD4D0,'Y' union allselect 0XD4D1,0XD7F9,'Z'                select top 1 @sql=@sql+letter from @maco where @char between bcode and ecode                 set @cyc = @cyc + 1             end        return @sql    endgo--建立取漢字首字母函數(第四版)create function [dbo].[f_getpy_V4](@col varchar(1000))returns varchar(1000)    begin        declare @cyc int,@len int,@sql varchar(1000),@char varbinary(20)        select @cyc = 1,@len = len(@col),@sql = ''        while @cyc <= @len             begin                  select @char = cast(substring(@col, @cyc, 1) as varbinary)if @char>=0XB0A1 and @char<=0XB0C4      set @sql=@sql+'A'else if @char>=0XB0C5 and @char<=0XB2C0 set @sql=@sql+'B'else if @char>=0XB2C1 and @char<=0XB4ED set @sql=@sql+'C'else if @char>=0XB4EE and @char<=0XB6E9 set @sql=@sql+'D'else if @char>=0XB6EA and @char<=0XB7A1 set @sql=@sql+'E'else if @char>=0XB7A2 and @char<=0XB8C0 set @sql=@sql+'F'else if @char>=0XB8C1 and @char<=0XB9FD set @sql=@sql+'G'else if @char>=0XB9FE and @char<=0XBBF6 set @sql=@sql+'H'else if @char>=0XBBF7 and @char<=0XBFA5 set @sql=@sql+'J'else if @char>=0XBFA6 and @char<=0XC0AB set @sql=@sql+'K'else if @char>=0XC0AC and @char<=0XC2E7 set @sql=@sql+'L'else if @char>=0XC2E8 and @char<=0XC4C2 set @sql=@sql+'M'else if @char>=0XC4C3 and @char<=0XC5B5 set @sql=@sql+'N'else if @char>=0XC5B6 and @char<=0XC5BD set @sql=@sql+'O'else if @char>=0XC5BE and @char<=0XC6D9 set @sql=@sql+'P'else if @char>=0XC6DA and @char<=0XC8BA set @sql=@sql+'Q'else if @char>=0XC8BB and @char<=0XC8F5 set @sql=@sql+'R'else if @char>=0XC8F6 and @char<=0XCBF9 set @sql=@sql+'S'else if @char>=0XCBFA and @char<=0XCDD9 set @sql=@sql+'T'else if @char>=0XCDDA and @char<=0XCEF3 set @sql=@sql+'W'else if @char>=0XCEF4 and @char<=0XD1B8 set @sql=@sql+'X'else if @char>=0XD1B9 and @char<=0XD4D0 set @sql=@sql+'Y'else if @char>=0XD4D1 and @char<=0XD7F9 set @sql=@sql+'Z'                set @cyc = @cyc + 1             end        return @sql    endgo--建立取漢字首字母函數(第一版)create function [dbo].[f_getpy_V1] (@str nvarchar(4000))returns nvarchar(4000)asbegin    declare @word nchar(1),@py nvarchar(4000)    set @py=''    while len(@str)>0    begin       set @word=left(@str,1)       set @py = @py+ (case when unicode(@word) between 19968 and 19968+20901                          then (       select top 1 py       from       (       select 'a' as py, N'驁' as word       union all select 'B',N'簿'       union all select 'C',N'錯'       union all select 'D',N'鵽'       union all select 'E',N'樲'       union all select 'F',N'鰒'       union all select 'G',N'腂'       union all select 'H',N'夻'       union all select 'J',N'攈'       union all select 'K',N'穒'       union all select 'L',N'鱳'       union all select 'M',N'旀'       union all select 'N',N'桛'       union all select 'O',N'漚'       union all select 'P',N'曝'       union all select 'Q',N'囕'       union all select 'R',N'鶸'       union all select 'S',N'蜶'       union all select 'T',N'籜'       union all select 'W',N'鶩'       union all select 'X',N'鑂'       union all select 'Y',N'韻'       union all select 'Z',N'咗'       ) T       where word>=@word collate Chinese_PRC_CS_AS_KS_WS       order by py asc       )       else @word       end)       set @str=right(@str,len(@str)-1)    end    return @PYendgo--建立取漢字首字母函數(第二版)create function [dbo].[f_getpy_V2](@Str varchar(500)='')returns varchar(500)asbegin    declare @strlen int,@return varchar(500),@ii int    declare @n int,@c char(1),@chn nchar(1)    select @strlen=len(@str),@return='',@ii=0    set @ii=0    while @ii<@strlen    begin       select @ii=@ii+1,@n=63,@chn=substring(@str,@ii,1)       if @chn>'z'       select @n = @n +1       ,@c = case chn when @chn then char(@n) else @c end       from(       select top 27 * from (       select chn = '吖'       union all select '八'       union all select '嚓'       union all select '咑'       union all select '妸'       union all select '發'       union all select '旮'       union all select '鉿'       union all select '丌' --because have no 'i'       union all select '丌'       union all select '哢'       union all select '垃'       union all select '嘸'       union all select '拏'       union all select '噢'       union all select '妑'       union all select '七'       union all select '呥'       union all select '仨'       union all select '他'       union all select '屲' --no 'u'       union all select '屲' --no 'v'       union all select '屲'       union all select '夕'       union all select '丫'       union all select '帀'       union all select @chn) as a       order by chn COLLATE Chinese_PRC_CI_AS       ) as b       else set @c='a'       set @return=@return+@c    end    return(@return)end--思路基本是一樣的，但是不同類型導致效率上有差別，這個差別不同環境測試出來的效果竟然不一樣。    select dbo.f_getpy_V1('我是一個土生土長的中國人') select dbo.f_getpy_V2('我是一個土生土長的中國人') select dbo.f_getpy_V3('我是一個土生土長的中國人') select dbo.f_getpy_V4('我是一個土生土長的中國人') --我現在測試到的開銷百分比是：--1:2:3:4 對應 18%:38%:44%:0%--如果你感興趣也可以在本地測試一下，看看執行計畫，這4個函數哪個最高效呢？可以把開銷百分比留言在下面，謝謝！