Ngay cả một số khả năng được tối ưu hóa cũng có. Đây là hai hàm sử dụng Sắp xếp bong bóng để sắp xếp các ký tự.
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
Chức năng 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
Kết quả:
select dbo.udf_SortString('zxcvbfgrtyuijklm')
--Returns bcfgijklmrtuvxyz
