SQL Server UDF to pad a string

http://www.mssqltips.com/sqlservertip/1738/sql-server-udf-to-pad-a-string/

declare @l varchar(50)
set @l='3 '
select @l=ltrim(rtrim('3'))
select len(@l)

SELECT RIGHT('000'+ISNULL(@l,''),3)

select left('00'+rtrim('3'),2)
--
select right('000'+ltrim(3),3)
--
SELECT RIGHT('000'+CAST(3 AS VARCHAR(3)),3)

--The function expects four parameters:
/*
附：oracle补零

1.前端补0：
Sql代码
select lpad('345',8,'0') from dual;
select to_char('345','00000000') from dual;  

select lpad('345',8,'0') from dual;  select to_char('345','00000000') from dual;
2.后端补0：
Sql代码
select rpad('345',8,'0') from dual;
select rpad('345',8,'0') from dual;
C#代码实现方法：
int a = 1;
string str = a.ToString("000");
//或
string astr = a.ToString().PadLeft(3,'0');

http://www.mssqltips.com/sqlservertip/1738/sql-server-udf-to-pad-a-string/
@string_unpadded - the raw string value you wish to pad.
@pad_char - the single character to pad the raw string.
@pad_count - the amount of times to repeat the padding character
@pad_pattern -  an integer value that determines where to insert the pad character
0 - all pad characters placed left of the raw string value (pad left)
1 - all pad characters placed right of the raw string value (pad right)
2 - all pad characters placed at the midpoint of the raw string value (pad center)
3 - the raw string value will be centered between the pad characters (pad ends)
*/
if object_id('[dbo].[usp_pad_string]') is not null
drop function [dbo].[usp_pad_string]
go
CREATE FUNCTION [dbo].[usp_pad_string]
 (
 @string_unpadded VARCHAR(100),
 @pad_char VARCHAR(1),
 @pad_count tinyint,
 @pad_pattern INT)
RETURNS VARCHAR(100)
AS
BEGIN
 DECLARE @string_padded VARCHAR(100) 

 SELECT @string_padded =
 CASE @pad_pattern
   WHEN 0 THEN REPLICATE(@pad_char, @pad_count) + @string_unpadded --pad left
   WHEN 1 THEN @string_unpadded + REPLICATE(@pad_char, @pad_count) --pad right
   WHEN 2 THEN
     --pad center
     LEFT(@string_unpadded, FLOOR(LEN(@string_unpadded)/2))
     + REPLICATE(@pad_char, @pad_count)
     + RIGHT(@string_unpadded, LEN(@string_unpadded) - FLOOR(LEN(@string_unpadded)/2))
   WHEN 3 THEN
     --pad edges
     REPLICATE(@pad_char, FLOOR(@pad_count/2))
     + @string_unpadded
     + REPLICATE(@pad_char, @pad_count - FLOOR(@pad_count/2))
 END
 RETURN @string_padded
END
GO
--測試
--Even distribution possible
--Pad Left
SELECT '1234' AS [raw string], dbo.[usp_pad_string]('1234', 'X', 4, 0) AS [padded string], '0 - pad LEFT' AS [pad pattern value]; 

--Pad Right
SELECT '1234' AS [raw string], dbo.[usp_pad_string]('1234', 'X', 4, 1) AS [padded string], '1 - pad RIGHT' AS [pad pattern value]; 

--Pad Center
SELECT '1234' AS [raw string], dbo.[usp_pad_string]('1234', 'X', 4, 2) AS [padded string], '2 - pad CENTER' AS [pad pattern value]; 

--Pad Edges
SELECT '1234' AS [raw string], dbo.[usp_pad_string]('1234', 'X', 4, 3) AS [padded string], '3 - pad EDGES' AS [pad pattern value];

--在右边加几位
declare @l varchar(20),@len int,@count int
set @l='1'
select @len=len(@l)
if(@len<6)
select @count=6-@len
select [dbo].[usp_pad_string] (@l,'0',@count,1)

--
select [dbo].[usp_pad_string] ('1','0',6-len('1'),1)