Generate comma separated integer days for SQL Server Partition Function

generate-int-days.csl

let endDate = datetime(2019-04-28);
range day from endDate - 120d to endDate step 1d
| summarize days = makelist(replace("-", "", substring(day, 0, 10)))
| project array_strcat(days, ", ")

Output of above query is

20181229, 20181230, 20181231, 20190101, 20190102, 20190103, 20190104, 20190105, 20190106, 20190107, 20190108, 20190109, 20190110, 20190111, 20190112, 20190113, 20190114, 20190115, 20190116, 20190117, 20190118, 20190119, 20190120, 20190121, 20190122, 20190123, 20190124, 20190125, 20190126, 20190127, 20190128, 20190129, 20190130, 20190131, 20190201, 20190202, 20190203, 20190204, 20190205, 20190206, 20190207, 20190208, 20190209, 20190210, 20190211, 20190212, 20190213, 20190214, 20190215, 20190216, 20190217, 20190218, 20190219, 20190220, 20190221, 20190222, 20190223, 20190224, 20190225, 20190226, 20190227, 20190228, 20190301, 20190302, 20190303, 20190304, 20190305, 20190306, 20190307, 20190308, 20190309, 20190310, 20190311, 20190312, 20190313, 20190314, 20190315, 20190316, 20190317, 20190318, 20190319, 20190320, 20190321, 20190322, 20190323, 20190324, 20190325, 20190326, 20190327, 20190328, 20190329, 20190330, 20190331, 20190401, 20190402, 20190403, 20190404, 20190405, 20190406, 20190407, 20190408, 20190409, 20190410, 20190411, 20190412, 20190413, 20190414, 20190415, 20190416, 20190417, 20190418, 20190419, 20190420, 20190421, 20190422, 20190423, 20190424, 20190425, 20190426, 20190427, 20190428