Extract substring from offset to space or full stop

[Mimi Cafe]

I used MySQL substr function to extra 100 characters from the result of a
query, but understandably, I don't get what I want.

 

Now I looked at Perl's substr function and it doesn't look like it can help
me achieve what I need to.

 

Let's say I have:

 

$s = "The black cat climbed the green tree";

$substring = substr( $s, 1, 15); # this will return "The black cat c".

 

How can I have this return the whole word climbed rather than the c (i.e. I
need to get "The black cat climbed")? I need to get the remaining characters
from the length till the next white space or end of a phrase.

 

Any other way to overcome this limitation?  How can I use regex here?