With the ASCII function you can return a certain character's ASCII value, as shown in the following example:
SELECT ASCII('A') AS A, ASCII('B') AS B,
ASCII('a') AS a, ASCII('b') AS b,
ASCII(1) AS [1], ASCII(2) AS [2],
ASCII('!') AS [!], ASCII('@') AS [@],
ASCII('\') AS [\], ASCII('/') AS [/]