Hi,
you do not have to enclose the whole statement in double quotes. What I meant and described is for the case that your values set and compared against the columns are character based that they should be enclosed in single quotes.
For example if you compare the value 'abc' in a where clause against a character based column it should like '... where mycolumn = ''' || :lv_value || ''''.
Regards,
Florian
PS: As you are using dynamic SQL you should always keep in mind to check your inputs to avoid SQL injections.