Imagine that you have a column with a bunch of fields like this:

```
ab
abc
abcd
...

```

I would like to transform these fields using a single query to something like this:

```
a_b
ab_c
abc_d
...

```

That is, inserting an underscore just before the last letter.

I could do it in a one by one basis:

```
update test set name = 'a_b' where name ='ab';
update test set name = 'ab_c' where name ='abc';
update test set name = 'abc_d' where name ='abcd';

```

But being a high number of fields to update, I figure there must be a better way to do this.