MySQL 8.0

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create table cust(Customer integer,Amount integer,Date_1 date,Period integer,Group_1 integer);
insert into cust values (77766,50,'2022-02-28',1,2);
insert into cust values (77766,20,'2022-03-31',2,2);
insert into cust values (77766,30,'2022-04-30',3,3);
insert into cust values (12345,50,'2022-02-28',1,1);
insert into cust values (12345,20,'2022-03-31',2,2);
insert into cust values (12345,30,'2022-04-30',3,3);
select * from cust;


Customer
Amount
Date_1
Period
Group_1


77766
50
2022-02-28
1
2

77766
20
2022-03-31
2
2

77766
30
2022-04-30
3
3

12345
50
2022-02-28
1
1

12345
20
2022-03-31
2
2

12345
30
2022-04-30
3
3


select *,
(select group_1 from cust a where a.customer = b.customer and period=1) Group_Period1,
(select group_1 from cust a where a.customer = b.customer and period=2) Group_Period2,
(select group_1 from cust a where a.customer = b.customer and period=3) Group_Period3 
from cust b;


Customer
Amount
Date_1
Period
Group_1
Group_Period1
Group_Period2
Group_Period3


77766
50
2022-02-28
1
2
2
2
3

77766
20
2022-03-31
2
2
2
2
3

77766
30
2022-04-30
3
3
2
2
3

12345
50
2022-02-28
1
1
1
2
3

12345
20
2022-03-31
2
2
1
2
3

12345
30
2022-04-30
3
3
1
2
3

Customer	Amount	Date_1	Period	Group_1
77766	50	2022-02-28	1	2
77766	20	2022-03-31	2	2
77766	30	2022-04-30	3	3
12345	50	2022-02-28	1	1
12345	20	2022-03-31	2	2
12345	30	2022-04-30	3	3