This may work for you:
set define off
Otherwise the ampersand needs to be at the end of a string,
'StackOverflow &' || ' you'
EDIT: I was click-happy when saving... This was referenced from a blog.
If you sometimes use substitution variables you might not want to turn define off. In these cases you could convert the ampersand from its numeric equivalent as in || Chr(38) || or append it as a single character as in || '&' ||.
|| Chr(38) ||
|| '&' ||
I resolved with the code below:
set escape on
and put a \ beside & in the left 'value_\&_intert'
'value_\&_intert'
Att