Oracle 18c

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Create table employees(
 employee_id NUMBER(6),
 first_name VARCHAR2(20),
 last_name VARCHAR2(20),
card_num VARCHAR2(10),
work_days VARCHAR2(7)
);
insert into employees (employee_id, first_name, last_name, card_num,  work_days)
with loop1(employee_id) as (select level from
 dual connect by level <= 50)
    ,loop2(b) as (select level from dual connect by level <= 7)

SELECT employee_id,
CASE round(dbms_random.value(1,20))
        WHEN 1 THEN 'Albert'
        WHEN 2 THEN 'Tom'
        WHEN 3 THEN 'Anna'
        WHEN 4 THEN 'Ty'
        WHEN 5 THEN 'Andy'
        WHEN 6 THEN 'Thomas'
        WHEN 7 THEN 'Alan'
        WHEN 8 THEN 'Tara'
        WHEN 9 THEN 'Cheryl'
        WHEN 10 THEN 'Ed'
        WHEN 11 THEN 'Steve'
        WHEN 12 THEN 'Mel'
        WHEN 13 THEN 'Micheal'
        WHEN 14 THEN 'Ron'
        WHEN 15 THEN 'Donald'
        WHEN 16 THEN 'Donny'
        WHEN 17 THEN 'Racheal'
        WHEN 18 THEN 'Debbie'
        WHEN 19 THEN 'Madison'
        WHEN  20 THEN 'Danny'
     END AS first_name,

 CASE  round(dbms_random.value(1,20))
        WHEN 1 THEN 'Andrews'
        WHEN 2 THEN 'Thorton'
        WHEN 3 THEN 'Smith'
        WHEN 4 THEN 'Jones'
        WHEN 5 THEN 'Ott'
        WHEN 6 THEN 'Stevens'
        WHEN 7 THEN 'Feldman'
        WHEN 8 THEN 'Stein'
        WHEN 9 THEN 'Ross'
        WHEN 10 THEN 'Eden'
        WHEN 11 THEN 'Saltzman'
        WHEN 12 THEN 'Kramer'
        WHEN 13 THEN 'Monroe'
        WHEN 14 THEN 'Hanks'
        WHEN 15 THEN 'Dunn'
        WHEN 16 THEN 'Dunbar'
        WHEN 17 THEN 'Rucker'
        WHEN 18 THEN 'Silverberg'
        WHEN 19 THEN 'Daniels'
        WHEN  20 THEN 'Kahn'
     END AS last_name,

 dbms_random.string('X',        dbms_random.value(5, 10))  AS card_num,

      replace(listagg(CASE round(dbms_random.value(1,2))
                       WHEN 1 THEN 'Y'
                       WHEN 2 THEN 'N'
                      END,',')               within group (order by b)
             ,',') AS work_days
  FROM  loop1
    cross join loop2
 group by employee_id;
50 rows affected

create or replace function dec2yn ( n number )
return varchar2
deterministic
is
  binval varchar2( 7 ) := '' ;
  n2     pls_integer := mod( n, 128 ) ;  -- allow decimals between 0 and 127 only
begin
  if n2 = 0 then return 'NNNNNNN' ;
  else
    while ( n2 > 0 ) loop
       binval := mod( n2, 2) || binval;
       n2 := trunc( n2 / 2 );
    end loop;
    binval := lpad( binval, 7, '0' ) ;          -- add 0 padding
    binval := translate( binval, '01', 'NY') ;  -- translate: 0 to N and 1 to Y
    return binval;
  end if ;
end dec2yn;
/
alter table employees
add (
  new_work_days varchar2( 4000 ) generated always as (
     dec2yn(employee_id )
  ) virtual
) ;
select employee_id, first_name, last_name, new_work_days from employees ;


EMPLOYEE_ID
FIRST_NAME
LAST_NAME
NEW_WORK_DAYS


1
Steve
Dunbar
NNNNNNY

2
Ron
Andrews
NNNNNYN

3
Anna
Stein
NNNNNYY

4
Steve
Monroe
NNNNYNN

5
Thomas
Monroe
NNNNYNY

6
Ty
Feldman
NNNNYYN

7
Donald
Smith
NNNNYYY

8
Ron
Hanks
NNNYNNN

9
Anna
Dunbar
NNNYNNY

10
Ron
Thorton
NNNYNYN

11
Anna
Dunbar
NNNYNYY

12
Donny
Andrews
NNNYYNN

13
Donald
Kramer
NNNYYNY

14
Ty
Ott
NNNYYYN

15
Micheal
Monroe
NNNYYYY

16
Tara
Feldman
NNYNNNN

17
Ed
Kramer
NNYNNNY

18
Steve
Feldman
NNYNNYN

19
Mel
Jones
NNYNNYY

20
Donald
Ott
NNYNYNN

21
Alan
Eden
NNYNYNY

22
Donald
Dunbar
NNYNYYN

23
Cheryl
Feldman
NNYNYYY

24
Ty
Monroe
NNYYNNN

25
Mel
Ross
NNYYNNY

26
Tara
Smith
NNYYNYN

27
Tom
Dunn
NNYYNYY

28
Cheryl
Ott
NNYYYNN

29
Ed
Daniels
NNYYYNY

30
Tara
Monroe
NNYYYYN

31
Micheal
Rucker
NNYYYYY

32
Ed
Dunn
NYNNNNN

33
Ed
Feldman
NYNNNNY

34
Ron
Kramer
NYNNNYN

35
Danny
Dunbar
NYNNNYY

36
Debbie
Jones
NYNNYNN

37
Cheryl
Monroe
NYNNYNY

38
Tom
Eden
NYNNYYN

39
Anna
Stevens
NYNNYYY

40
Ron
Stein
NYNYNNN

41
Donald
Stein
NYNYNNY

42
Tara
Kramer
NYNYNYN

43
Ty
Kramer
NYNYNYY

44
Racheal
Rucker
NYNYYNN

45
Tara
Ross
NYNYYNY

46
Mel
Kramer
NYNYYYN

47
Ron
Feldman
NYNYYYY

48
Donald
Eden
NYYNNNN

49
Madison
Dunn
NYYNNNY

50
Ed
Dunbar
NYYNNYN

EMPLOYEE_ID	FIRST_NAME	LAST_NAME	NEW_WORK_DAYS
1	Steve	Dunbar	NNNNNNY
2	Ron	Andrews	NNNNNYN
3	Anna	Stein	NNNNNYY
4	Steve	Monroe	NNNNYNN
5	Thomas	Monroe	NNNNYNY
6	Ty	Feldman	NNNNYYN
7	Donald	Smith	NNNNYYY
8	Ron	Hanks	NNNYNNN
9	Anna	Dunbar	NNNYNNY
10	Ron	Thorton	NNNYNYN
11	Anna	Dunbar	NNNYNYY
12	Donny	Andrews	NNNYYNN
13	Donald	Kramer	NNNYYNY
14	Ty	Ott	NNNYYYN
15	Micheal	Monroe	NNNYYYY
16	Tara	Feldman	NNYNNNN
17	Ed	Kramer	NNYNNNY
18	Steve	Feldman	NNYNNYN
19	Mel	Jones	NNYNNYY
20	Donald	Ott	NNYNYNN
21	Alan	Eden	NNYNYNY
22	Donald	Dunbar	NNYNYYN
23	Cheryl	Feldman	NNYNYYY
24	Ty	Monroe	NNYYNNN
25	Mel	Ross	NNYYNNY
26	Tara	Smith	NNYYNYN
27	Tom	Dunn	NNYYNYY
28	Cheryl	Ott	NNYYYNN
29	Ed	Daniels	NNYYYNY
30	Tara	Monroe	NNYYYYN
31	Micheal	Rucker	NNYYYYY
32	Ed	Dunn	NYNNNNN
33	Ed	Feldman	NYNNNNY
34	Ron	Kramer	NYNNNYN
35	Danny	Dunbar	NYNNNYY
36	Debbie	Jones	NYNNYNN
37	Cheryl	Monroe	NYNNYNY
38	Tom	Eden	NYNNYYN
39	Anna	Stevens	NYNNYYY
40	Ron	Stein	NYNYNNN
41	Donald	Stein	NYNYNNY
42	Tara	Kramer	NYNYNYN
43	Ty	Kramer	NYNYNYY
44	Racheal	Rucker	NYNYYNN
45	Tara	Ross	NYNYYNY
46	Mel	Kramer	NYNYYYN
47	Ron	Feldman	NYNYYYY
48	Donald	Eden	NYYNNNN
49	Madison	Dunn	NYYNNNY
50	Ed	Dunbar	NYYNNYN