A basic lintcode MySQL database problem

https://www.lintcode.com/problem/1927/solution/42138
Or do it according to normal thinking .
But I saw a person's way of solving problems , I don't understand .
His answer is like this =

UPDATE coins SET side = char(ascii(side)^30)

---

Take the answer ：

Haven't you learned programming ？^ Express exclusive or . Here you are ascii clock ：

You calculate ,p Of ascii Code is 112,112 Exclusive or 30=110, That is to say n,110 Exclusive or 30=112, That is to say p.

The inverse operation of XOR is itself .

---