SQL Server 2019

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CREATE TABLE invoices
(
invoice VARCHAR(20) NOT NULL,
quantity INT NOT NULL,
price INT NOT NULL,
summ INT NOT NULL, 
account INT NOT NULL,
);
INSERT invoices(invoice, quantity, price, summ, account) 
VALUES ('ty20210110', 2, 100, 200, 1001);
INSERT invoices(invoice, quantity, price, summ, account) 
VALUES ('ty20210110', 3, 100, 300, 1002);
INSERT invoices(invoice, quantity, price, summ, account) 
VALUES ('ty20210110', 1, 250, 250, 1001);
INSERT invoices(invoice, quantity, price, summ, account) 
VALUES ('ty20210110', 2, 120, 240, 1002);
INSERT invoices(invoice, quantity, price, summ, account) 
VALUES ('ty20210110', 4, 100, 400, 1002);
INSERT invoices(invoice, quantity, price, summ, account) 
VALUES ('ty20210114', 3, 100, 300, 1001);
INSERT invoices(invoice, quantity, price, summ, account) 
VALUES ('ty20210114', 5, 80, 400, 1003);
INSERT invoices(invoice, quantity, price, summ, account) 
VALUES ('ty20210114', 5, 100, 500, 1004);

SELECT invoices.invoice, invoices.summ,  accounts = STUFF(
             (SELECT DISTINCT ',' + Convert(varchar, invoices.account, 60) 
              FROM invoices
              FOR XML PATH (''))
             , 1, 1, '')
FROM invoices
GROUP BY invoices.invoice, invoices.summ

invoice	summ	accounts
ty20210110	200	1001,1002,1003,1004
ty20210110	240	1001,1002,1003,1004
ty20210110	250	1001,1002,1003,1004
ty20210110	300	1001,1002,1003,1004
ty20210110	400	1001,1002,1003,1004
ty20210114	300	1001,1002,1003,1004
ty20210114	400	1001,1002,1003,1004
ty20210114	500	1001,1002,1003,1004