Hello,

With this regex : not REGEXP_LIKE (categories, '[^(subcat1| subcat2 |subcat3|null; )]', 'i'), i can specified what kind of values i can be used and this are separated with ';'.
but i can do that

insert into regexText Values(';') 
insert into regexTest Values('subcat1 subcat2)
insert into regexTest Values ('subcat1;)
insert into regexTest values('subcat1;null)

but insert into regexTest Values ('null') is allowed
and i want to correct my regex so that this insertion are not allowed.

Therefore i do that

Create Table regexTest(
categories VARCHAR2(1000) constraints check_ValidValue check(not regexp_like(categories,'^[(subcat1|subcat2|subcat3|null)];[(subcat1|subcat2|subcat3)]*;[(subcat1|subcat2|subcat3)]*')) 

)

but this did not work how i have expected.

----------------------------------------------------------------------------------------------------------------------------------
Hi chris ,
the purpose of this task is to add comma delimited string in a cell.
I have to determine a list of value that can be add in a cell.Although there are many string to be add.
e.g : the allowed value are : subcat1, subcat2,subcat3,subcat4.
i can insert in a cell : subcat1;subcat2;subcat3 Or subcat1 or subcat2;subcat1 or the value null. And when i insert the value null i can not insert anything else.

I can not insert: subcat1;subcat5 or subcat5 or subcat1; or ;

This symbols are to be allowed in the string : &,- and spaces.
And after ';' i can used spaces or not.

allowed values : subcat1
subcat2
subcat3
subcat4
The Data
A & B
A-B

Code that meets requirements :

insert into regexText Values('subcat1') 
insert into regexText Values('subcat1; subcat3') 
insert into regexText Values('subcat3; subcat4') 
insert into regexText Values('null') 
insert into regextext Values ('the data; subcat4)
insert into regexText Values('A & B; the data') 
insert into regexText Values('A & B; A-B; subcat2') 

Code that does not meet requirements:

insert into regexText Values(';') 
insert into regexText Values('subcat1;') 
insert into regexText Values('null; subcat4') 
insert into regexText Values('subcat4; null') 
insert into regexText Values('subcat7') 
insert into regexText Values('subcat1; subcat6) 

I thought that with a regex i can solve this problem but it appears difficult.
I don't know if there are an another way to solve this problem.
Thanks for the answer

set define off
create table regexText (
  x varchar2(20)
);

alter table regexText add constraint c check (
  x in ('subcat1', 'subcat1; subcat3','subcat3; subcat4', 'null', 
        'the data; subcat4', 'A & B; the data', 'A & B; A-B; subcat2') 
);

create table allowed_vals (
  x varchar2(20) not null primary key
);

insert into allowed_vals Values('subcat1') ;
insert into allowed_vals Values('subcat1; subcat3') ;
insert into allowed_vals Values('subcat3; subcat4') ;
insert into allowed_vals Values('null') ;
insert into allowed_vals Values ('the data; subcat4');
insert into allowed_vals Values('A & B; the data') ;
insert into allowed_vals Values('A & B; A-B; subcat2') ;
commit;

alter table regexText add constraint fk 
  foreign key (x) references allowed_vals (x);