SQL Server - 计算两个字符之间的字符数

Question

如何计算两个字符之间的字母数(按字母顺序a到z或z到a)？

例如:

WITH    ExampleData
          AS ( SELECT   'a' AS StartChar, 'e' AS EndChar
               UNION ALL
               SELECT   'm', 'r'
               UNION ALL
               SELECT   'f', 'a'
             )
    SELECT  StartChar ,
            EndChar
    FROM    ExampleData

需要生产:

StartChar   EndChar    Diff
a           e          4
m           r          5
f           a          -5

我看到如何使用udf和while循环轻松完成,但我想知道是否有更快的方法？

Answer 1

SELECT StartChar, EndChar, ASCII(EndChar) - ASCII(StartChar) AS Diff
FROM ExampleData

SQL小提琴示例