-- =============================================

-- 作    者: ruijc

-- 描    述: 將Url編碼轉明文字符串

-- =============================================

CREATE FUNCTION FN_URLDecode

(

 @Str VARCHAR(8000)--已經編碼的字符串

)

RETURNS VARCHAR(8000)

AS

BEGIN

  DECLARE @Position  INT;          --'%'字符所在位置

  DECLARE @Chr       CHAR(16);     --字符常量

  DECLARE @Pattern   CHAR(21);

  DECLARE @ParseStr  VARCHAR(8000);--解碼后的字符串

  DECLARE @Hex		 UNIQUEIDENTIFIER;--定義16進制模板,因為GUID方便轉為BYTE

  DECLARE @CurrWord	 INT		;--當前字

  DECLARE @BitsCount INT        ;--當前解碼位數

  DECLARE @HightByte TINYINT;--高位字節

  DECLARE @LowByte   TINYINT;--低位字節

  

  /****************變量初始化***********************/

  SET     @Chr = '0123456789abcdef';

  SET     @Pattern = '%[%][a-f0-9][a-f0-9]%';

  SET     @ParseStr=@Str;

  SET     @Hex= '00000000-0000-0000-0000-000000000000';

  SET     @CurrWord=0;

  SET     @BitsCount=0;

  SET     @HightByte=0;

  SET     @LowByte=0;

  

  IF (@Str IS NOT NULL OR @Str<>'')

   BEGIN

     SET    @Position = PATINDEX(@Pattern, @ParseStr);--取得第一個'%'所在的位置

     WHILE @Position>0

      BEGIN

        SET @Hex=STUFF(@Hex,7,2,LEFT(RIGHT(@ParseStr,len(@ParseStr) - @Position),2));

        SET @HightByte=CAST(CAST(@Hex AS BINARY(1)) AS INT);

        

        IF (@HightByte & 127=@HightByte)

         BEGIN--ASCII碼直接轉為UTF-8或UTF-16

           SET @CurrWord=@HightByte;

           SET @BitsCount=1;

         END

         

        IF (@HightByte & 192=192)

         BEGIN--Unicode編碼

           SET @CurrWord=@HightByte & 31 ;

           SET @BitsCount=2;

         END



        IF (@HightByte & 224=224)

         BEGIN--UTF-8編碼

			SET	@CurrWord = @HightByte & 15

			SET @BitsCount = 3	

         END



        IF (@HightByte & 240=240)

         BEGIN--UTF-16編碼

			SET	@CurrWord = @HightByte & 7

			SET @BitsCount = 4	

         END



        DECLARE @Index INT;        

        DECLARE @NEWCHAR NVARCHAR(2);

        SET @Index=1;

        SET @NEWCHAR='';

        WHILE @Index<@BitsCount

         BEGIN

              IF (LEN(@ParseStr)-@Position-3*@Index)<0

               BEGIN

                   SET @ParseStr=@Str ;   

                   SET @Position=0;

                   BREAK;              

               END

			SET @NEWCHAR = LEFT(RIGHT(@ParseStr,LEN(@ParseStr) - @Position - 3* @Index),2);	  

            --如果沒有16進制編碼則中斷外層WHILE

			IF @NEWCHAR NOT LIKE '[a-f0-9][a-f0-9]'

			 BEGIN

				SET @ParseStr = @Str

				SET @Position=0;--中斷外層WHILE

				BREAK;

			 END 	



			SET @Hex = STUFF(@Hex, 7, 2, @NEWCHAR)		



			SET @LowByte = CAST(CAST(@Hex AS BINARY(1)) AS INT);



			IF @LowByte&192=192

			BEGIN

				SET @ParseStr = @Str

				SET @Position=0;--中斷外層WHILE

				BREAK;

			END 

			

			SET @CurrWord = (@CurrWord * 64) | (@LowByte & 63)				

			SET @Index =@Index+ 1						  			             

         END                                   



		 IF @BitsCount > 1           

          SET @ParseStr = STUFF(@ParseStr, @Position, 3*(@BitsCount), NCHAR(@CurrWord))

		 ELSE 

		  BEGIN

			set @ParseStr = STUFF(@ParseStr, @Position, 2, NCHAR(@CurrWord))

			set @ParseStr = STUFF(@ParseStr, @Position+1, 1, N'')		

		  END

		----取得下一個'%'所在的位置

        SET  @Position = PATINDEX(@Pattern, @ParseStr);

      END

   END

   RETURN @ParseStr;

END



GO

SELECT dbo.FN_URLDecode('%E4%BD%A0%E6%98%AF%E5%93%AA%E4%B8%AA')


  

SQL 將URL編碼轉漢字！