How to find out "standard"/datetime format in MSSQL DB?

Question

SQL

By the method of scientific poke, I found out that mssql correctly accepts the datetime type when you write it like this. At first I tried to add a date in this format, but it gave an error. So, as I understand it, the date type is in the YYYY-DD-MM format. Then I ran a query to see if there was any information about how to insert the date. Got this response
insert into testtable values ('1990-26-07')
insert into testtable values ('1990-07-26')
sp_helplanguage @@language

21	dmy	1	0	русский	Russian	Январь,Февраль,Март,Апрель,Май,Июнь,Июль,Август,Сентябрь,Октябрь,Ноябрь,Декабрь	янв,фев,мар,апр,май,июн,июл,авг,сен,окт,ноя,дек	понедельник,вторник,среда,четверг,пятница,суббота,воскресенье	1049	1049

in which dateformat = dmy, which does not match the format that worked for me O_0

Answer 1

Date-time string constant in MS SQL