Oracle 18c

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CREATE TABLE employees AS
SELECT level AS employee_id,
  CASE round(dbms_random.value(1,3)) 
        WHEN 1 THEN 'Albert' 
        WHEN 2 THEN 'Tom' 
        WHEN 3 THEN 'Anna'
     END AS first_name,

  CASE  round(dbms_random.value(1,3)) 
        WHEN 1 THEN 'Andrews' 
        WHEN 2 THEN 'Thorton' 
        WHEN 3 THEN 'Smith'
     END AS last_name, 
  dbms_random.string('X', dbms_random.value(5, 10))  AS card_num

FROM   dual
CONNECT BY level <= 50;
50 rows affected

alter table employees add work_days VARCHAR2(7);
update employees set work_days = 
  (select wd from (
    select level id, substr(wd, level, 7) wd
      from (select listagg(case when dbms_random.value(0, 1) <.5 then 'Y' else 'N' end) 
                   within group (order by null) wd
              from dual connect by level <= 7*50)
      connect by level < 50 )
   where id = employees.employee_id)
50 rows affected

select * from employees


EMPLOYEE_ID
FIRST_NAME
LAST_NAME
CARD_NUM
WORK_DAYS


1
Albert
Thorton
BHVN5QJH
NNYNYYY

2
Albert
Andrews
8FT0XA
YYNYNYN

3
Tom
Smith
BL21DA4FS
NYNNNYY

4
Tom
Thorton
SFSG8THZ
YYNNNYY

5
Albert
Andrews
IRYRSN
YYNYNYY

6
Tom
Thorton
9CIGVQA
YYYYNYN

7
Albert
Thorton
L2E3H4J
YNNYNNN

8
Anna
Thorton
0LHE5
YYYYYNN

9
Anna
Smith
26XQW6
YNNNYNY

10
Tom
Andrews
HO8I52HR
NNNYYYN

11
Anna
Thorton
1WQ6N
NYNNNNN

12
Tom
Thorton
920ICOUG
YNYYYNY

13
Tom
Thorton
GPXMW0Z5X
YNNNNYY

14
Anna
Smith
OJRJVHIPYB
NYYNYYY

15
Albert
Andrews
JBB99DR94T
NYYNNNY

16
Anna
Smith
XZTZK
YNNNNNN

17
Tom
Thorton
70BXKHI6T
YYYYYNN

18
Albert
Andrews
2THX2
YNYNYYN

19
Tom
Andrews
HPZ3XDF5
YNYNYYN

20
Anna
Smith
A79L7YAK
YNYYNYN

21
Tom
Thorton
V9LDLIQ1T
NYNNYYY

22
Albert
Smith
12KCZ5
YNYYYNY

23
Tom
Thorton
HW1E7PL
YYYYYYY

24
Anna
Smith
JEE2FFD
NYYYNNN

25
Anna
Smith
WO34PS
NNNNNNY

26
Anna
Thorton
KANT53EC6
NNNYNYN

27
Tom
Andrews
FU8PR402
NYYNYYN

28
Tom
Thorton
3ZV0WW2QH
YNNNNYY

29
Tom
Thorton
X0IAYS
YYYYNNY

30
Tom
Andrews
451KN7QV
NNNNNYY

31
Tom
Thorton
5LJJF1H
YNYYYNN

32
Albert
Smith
4KTH1
NYNYNNN

33
Albert
Thorton
871UDV5
NYYYNYY

34
Tom
Thorton
8T3NF1
NYNNNNY

35
Anna
Andrews
A3GMCAETU
YNNNYYN

36
Anna
Thorton
L006R
NYNNNYN

37
Tom
Smith
515H1WLF0V
YYNNYYN

38
Albert
Smith
SWYZQLI7
NNNNYNY

39
Tom
Thorton
7MSBL
YNYYYYY

40
Tom
Andrews
EC1FX6U9Q
NYYYYYN

41
Albert
Thorton
23D26L1KLO
NYYYYNY

42
Tom
Andrews
8JUCU
NYYNNYN

43
Tom
Andrews
VEUIMT2
NNYYNYY

44
Anna
Thorton
W4F3EKCJ
NYYYYNN

45
Albert
Smith
KV9ENH4FC
YYYNYYY

46
Tom
Thorton
9T9155BHZ
NYNYYNN

47
Anna
Andrews
XYBADM
NNNNNYN

48
Tom
Smith
KHUGA6C
NYYYNYN

49
Anna
Thorton
BN9YUPWX9A
NYNNYNY

50
Albert
Smith
H30ZK0D9
null

EMPLOYEE_ID	FIRST_NAME	LAST_NAME	CARD_NUM	WORK_DAYS
1	Albert	Thorton	BHVN5QJH	NNYNYYY
2	Albert	Andrews	8FT0XA	YYNYNYN
3	Tom	Smith	BL21DA4FS	NYNNNYY
4	Tom	Thorton	SFSG8THZ	YYNNNYY
5	Albert	Andrews	IRYRSN	YYNYNYY
6	Tom	Thorton	9CIGVQA	YYYYNYN
7	Albert	Thorton	L2E3H4J	YNNYNNN
8	Anna	Thorton	0LHE5	YYYYYNN
9	Anna	Smith	26XQW6	YNNNYNY
10	Tom	Andrews	HO8I52HR	NNNYYYN
11	Anna	Thorton	1WQ6N	NYNNNNN
12	Tom	Thorton	920ICOUG	YNYYYNY
13	Tom	Thorton	GPXMW0Z5X	YNNNNYY
14	Anna	Smith	OJRJVHIPYB	NYYNYYY
15	Albert	Andrews	JBB99DR94T	NYYNNNY
16	Anna	Smith	XZTZK	YNNNNNN
17	Tom	Thorton	70BXKHI6T	YYYYYNN
18	Albert	Andrews	2THX2	YNYNYYN
19	Tom	Andrews	HPZ3XDF5	YNYNYYN
20	Anna	Smith	A79L7YAK	YNYYNYN
21	Tom	Thorton	V9LDLIQ1T	NYNNYYY
22	Albert	Smith	12KCZ5	YNYYYNY
23	Tom	Thorton	HW1E7PL	YYYYYYY
24	Anna	Smith	JEE2FFD	NYYYNNN
25	Anna	Smith	WO34PS	NNNNNNY
26	Anna	Thorton	KANT53EC6	NNNYNYN
27	Tom	Andrews	FU8PR402	NYYNYYN
28	Tom	Thorton	3ZV0WW2QH	YNNNNYY
29	Tom	Thorton	X0IAYS	YYYYNNY
30	Tom	Andrews	451KN7QV	NNNNNYY
31	Tom	Thorton	5LJJF1H	YNYYYNN
32	Albert	Smith	4KTH1	NYNYNNN
33	Albert	Thorton	871UDV5	NYYYNYY
34	Tom	Thorton	8T3NF1	NYNNNNY
35	Anna	Andrews	A3GMCAETU	YNNNYYN
36	Anna	Thorton	L006R	NYNNNYN
37	Tom	Smith	515H1WLF0V	YYNNYYN
38	Albert	Smith	SWYZQLI7	NNNNYNY
39	Tom	Thorton	7MSBL	YNYYYYY
40	Tom	Andrews	EC1FX6U9Q	NYYYYYN
41	Albert	Thorton	23D26L1KLO	NYYYYNY
42	Tom	Andrews	8JUCU	NYYNNYN
43	Tom	Andrews	VEUIMT2	NNYYNYY
44	Anna	Thorton	W4F3EKCJ	NYYYYNN
45	Albert	Smith	KV9ENH4FC	YYYNYYY
46	Tom	Thorton	9T9155BHZ	NYNYYNN
47	Anna	Andrews	XYBADM	NNNNNYN
48	Tom	Smith	KHUGA6C	NYYYNYN
49	Anna	Thorton	BN9YUPWX9A	NYNNYNY
50	Albert	Smith	H30ZK0D9	null