Alphabetical Addition

Notes:

  • Letters will always be lowercase.
  • Letters can overflow (see second to last example of the description)
  • If no letters are given, the function should return 'z'

Examples:

table(letter: ["a", "b", "c"]) = "f"
table(letter: ["a", "b"]) = "c"
table(letter: ["z"]) = "z"
table(letter: ["z", "a"]) = "a"
table(letter: ["y", "c", "b"]) = "d" -- notice the letters overflowing
table(letter: []) = "z"
  1. The SQL CHR function accepts an ASCII code and returns the corresponding character.
  2. The COALESCE function in SQL server is used to return the first Non-NULL value from the list of columns/arguments given in order.
  3. COALESCE is considered similar to writing a CASE statement expression in SQL.
SELECT COALESCE(CHR(CAST((SUM(ascii(letter) - 96)-1)%26 as int)+97), 'z')
as letter
FROM letters;

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