SQL Server 2017

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CREATE TABLE tablename
    ([conversationid] varchar(36), [participantid] varchar(36), [mediatype] varchar(8), [rownum] int)
;
    
INSERT INTO tablename
    ([conversationid], [participantid], [mediatype], [rownum])
VALUES
    ('01fda91b-6001-4904-b0bc-8c61aec654b4', '13f954cb-4acb-4ab9-89e7-c48ece23a043', 'callback', 1),
    ('01fda91b-6001-4904-b0bc-8c61aec654b4', '13f954cb-4acb-4ab9-89e7-c48ece23a043', 'voice', 2),
    ('0519386a-2b8f-403c-b65b-fd8cc3c09a32', 'b033fe2f-a58c-4973-8006-54561b5a5bf7', 'voice', 1),
    ('085adea7-1deb-45d8-ae61-639255a689ce', '4151d364-5740-4dcf-b756-9772efaacb26', 'voice', 1),
    ('0c50e9c5-cbe0-4da5-9a8c-976efea255b2', '8f1ee999-8454-4db9-8c24-68e773350f39', 'callback', 1),
    ('138da3c8-c118-4ddf-b294-57301261eb97', 'cf2b643e-b07f-46c8-a52c-0cb5492e6485', 'voice', 1),
    ('613c51c6-3c8b-4b53-91de-de3cc004fa92', '54a84468-e452-4820-9c8a-89904ff97d8d', 'callback', 1),
    ('613c51c6-3c8b-4b53-91de-de3cc004fa92', '54a84468-e452-4820-9c8a-89904ff97d8d', 'voice', 2)
;

8 rows affected

conversationid	participantid	mediatype	rownum
01fda91b-6001-4904-b0bc-8c61aec654b4	13f954cb-4acb-4ab9-89e7-c48ece23a043	callback	1
0519386a-2b8f-403c-b65b-fd8cc3c09a32	b033fe2f-a58c-4973-8006-54561b5a5bf7	voice	1
085adea7-1deb-45d8-ae61-639255a689ce	4151d364-5740-4dcf-b756-9772efaacb26	voice	1
0c50e9c5-cbe0-4da5-9a8c-976efea255b2	8f1ee999-8454-4db9-8c24-68e773350f39	callback	1
138da3c8-c118-4ddf-b294-57301261eb97	cf2b643e-b07f-46c8-a52c-0cb5492e6485	voice	1
613c51c6-3c8b-4b53-91de-de3cc004fa92	54a84468-e452-4820-9c8a-89904ff97d8d	callback	1