字母转为大写字母

 自定义Scalar-valued Function函数，把字母转换为大写字母。

字母转为大写字母a-->A;b-->B;c-->C;...z-->Z
如果非字母转换为''

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

-- =============================================
-- Author:      Insus.NET
-- Blog:        https://insus.cnblogs.com
-- Create date: 2019-05-31
-- Update date: 2019-05-31
-- Description: 字母转为大写字母a-->A;b-->B;c-->C;...z-->Z
--              如果非字母转换为''
-- =============================================
CREATE FUNCTION [dbo].[svf_ConvertLettertoUppercaseLetter] 
(
  @Letter CHAR(1)
) RETURNS CHAR(1)
AS
BEGIN
    DECLARE @UppercaseLetter CHAR(1) = ''          
    IF LEN(ISNULL(@Letter,'')) > 0 
    BEGIN
        IF ASCII(@Letter) % 97 + 1 <= 26
            SET @UppercaseLetter = CHAR(ASCII(@Letter) - (97 - 65)) 

        IF ASCII(@Letter) % 65 + 1 <= 26
            SET @UppercaseLetter = @Letter
    END      
    RETURN @UppercaseLetter
END
GO

Source Code

例子演示：

SELECT
[dbo].[svf_ConvertLettertoUppercaseLetter] ('A') AS 'A',
[dbo].[svf_ConvertLettertoUppercaseLetter] ('a') AS 'a',
[dbo].[svf_ConvertLettertoUppercaseLetter] ('B') AS 'B',
[dbo].[svf_ConvertLettertoUppercaseLetter] ('b') AS 'b',
[dbo].[svf_ConvertLettertoUppercaseLetter] ('C') AS 'C',
[dbo].[svf_ConvertLettertoUppercaseLetter] ('c') AS 'c',
[dbo].[svf_ConvertLettertoUppercaseLetter] ('Z') AS 'Z',
[dbo].[svf_ConvertLettertoUppercaseLetter] ('z') AS 'z',
[dbo].[svf_ConvertLettertoUppercaseLetter] ('$') AS '$'

Source Code