Même certaines possibilités optimisées sont là. Ici, deux fonctions utilisent le tri à bulles pour trier les caractères.
CREATE FUNCTION udf_SortString
(
@string VARCHAR(1000)
)
RETURNS VARCHAR(1000)
AS
BEGIN
DECLARE @len TINYINT
DECLARE @i TINYINT
DECLARE @currentchar CHAR(1)
DECLARE @swapped BIT
DECLARE @begin BIT
DECLARE @nextchar CHAR(1)
SET @begin = 1
SET @len = LEN(@string)
SET @i = 1
WHILE @begin = 1 OR @swapped = 1
BEGIN
SET @swapped = 0
SET @i = 1
SET @begin = 0
WHILE @i <= @len
BEGIN
SET @currentchar = SUBSTRING(@string, @i, 1)
SET @nextchar = SUBSTRING(@string, @i + 1, 1)
IF @currentchar > @nextchar AND (@nextchar > '')
BEGIN
SET @string = dbo.udf_swap(@string, @i, @i + 1)
SET @swapped = 1
END
SET @i = @i + 1
END
END
RETURN(@string)
END
Fonction 2 :
CREATE FUNCTION dbo.udf_Swap
(
@fullstring VARCHAR(1000),
@charlocation1 TINYINT,
@charlocation2 TINYINT
)
RETURNS VARCHAR(1000)
AS
BEGIN
DECLARE @returnval varchar(1000)
DECLARE @begin VARCHAR(1000), @middle VARCHAR(1000), @end VARCHAR(1000)
DECLARE @firstchar CHAR(1), @secondchar CHAR(1), @len INT
SET @fullstring = LTRIM(RTRIM(@fullstring))
SET @len = LEN(@fullstring)
IF @charlocation1 > @len OR @charlocation2 > @len
SET @returnval = @fullstring
ELSE
BEGIN
SET @firstchar = SUBSTRING(@fullstring, @charlocation1, 1)
SET @secondchar = SUBSTRING(@fullstring, @charlocation2, 1)
SET @begin = LEFT(@fullstring, (@charlocation1-1))
SET @middle = SUBSTRING(@fullstring, @charlocation1+1, (@[email protected])-1)
SET @end = SUBSTRING(@fullstring, @charlocation2+1, @len)
SET @returnval = @begin + @secondchar + @middle + @firstchar + @end
END
RETURN(@returnval)
END
Résultat :
select dbo.udf_SortString('zxcvbfgrtyuijklm')
--Returns bcfgijklmrtuvxyz
