Can anyone help me to get substring using [sed](http://en.wikipedia.org/wiki/Sed) program?

I have a file with this line:

```
....
define("BASE", "empty"); # there can be any string (not only "empty").
....

```

And I need to get "empty" as string variable to my bash script.

At this moment I have:

```
sed -n '/define(\"BASE\"/p' path/to/file.ext
# returns this line:
# define("BASE", "empty");
# but I need 'empty'

```

**UPD:** Thanks to [@Jaypal](https://stackoverflow.com/users/970195/jaypal)

For now I have bash script:

```
DBNAME=`sed -n '/define(\"BASE\"/p' path/to/file.ext`
echo $DBNAME | sed -r 's/.*"([a-zA-Z]+)".*/\1/'

```

It work OK, but if there any way to make the same manipulation with one line of code?