Passing a parameter value for like - sql

Question

create table ter (
ID number,
category varchar2(250 byte),
name varchar2(250 byte)
);
insert into ter values (1, 'amd-visual theraphy','john');
insert into ter values (1, 'amd-visual theraphy','mike');
insert into ter values (2, 'amd-autmatic theraphy','mike');
insert into ter values (3, 'amd-autmatic theraphy','drane');
insert into ter values (3, 'cmd autmatic theraphy', 'traverse');
insert into ter values (3, 'amd-dramatic theraphy','drane');
insert into ter values (3, 'cmd-dropertic theraphy', 'traverse');
insert into ter values (5,'qwd-dropertic visual-theraphy','drones');
insert into ter values (5,'qwd-aromatic-theraphy','drones');
insert into ter values (3, 'other', 'traverse');
insert into ter values (3, 'other', 'traverse');
1: &category is null display all records
2: &category is not null and if i enter category =visual,autmatic then display respectively
3 &category is not null and if i enter category =dramatic it should display dramtic and dropertic ignoring other results;
as dramatic and dropertic is the requirement where the user want to see and ignoring the if partial value matches with visual and autmatic contains
how to obtain this result
this is what one gave the solution to me but still i want to ignore the visual containing dropetic
select *
from ter t cross join (select '&category' as my_categ from dual) m
where m.my_categ is null
or m.my_categ in ('visual', 'autmatic', 'dramtic') and t.category like '%'
|| m.my_categ || '%'
or m.my_categ = 'dramtic' and t.category like '%dropertic%' ;

Answer 1

I'd change your data model a bit.
Instead of saving categories as a space separated string, i'd better move them to separate table.
create table category(
ter_id number,
name varchar(250 bytes)
);
where ter_id is the same as ID in your ter column.
This table should contain records like:
insert into category values (1, 'amd-visual');
insert into category values (1, 'therapy');
-- etc.
Implying above your query will be something like:
select t.*, c.*
from ter t, category c
where t.id = c.ter_id
and category in ('therapy', 'visual');
-- etc...
If you really need to satisfy criteria:
if category is null display all records
it's easy to implement just adding
record with empty category name to table category:
insert into category values (1, null);
insert into category values (2, null);
-- etc.