I discovered something strange today when I was trying to `select sum` from an ENUM field. It was adding 1 to the values! A sample table I used is shown below:

```
x     y
_______
3  |  2
0  |  1

```

Both *x* and *y* are `ENUM ('0','1','2','3')` 

My query is as follows:

```
select sum(x), sum(y), sum(x+y) from myfield

```

And the result is:

```
5    5   10

```

This is very strange. Does it mean that is this behaviour consistent? Can I use something like:

```
select sum(x - 1), sum(y - 1), sum((x-1)+(y-1)) from myfield

```

which will produce the correct results or is this behavior only peculiar to my db server in particular?

Thanks.

**EDIT:**
For those wondering why I'm using ENUM, it's because the actual field I'm using contains 'AR' which can't fit in into `tinyint`.