Oracle SQL escape character (for a '&')

Question

While attempting to execute SQL insert statements using Oracle SQL Developer I keep generating an \"Enter substitution value\" prompt:

insert into agregadore         


        

Answer 1

select 'one'||'&'||'two' from dual

Answer 2

Set the define character to something other than &

SET DEFINE ~
create table blah (x varchar(20));
insert into blah (x) values ('blah&amp');
select * from blah;

X                    
-------------------- 
blah&amp