Obviously knowing how to read, or better yet comprehend, documentation is a lost art.  And so is basic troubleshooting.  No, not going to post a link as there is no...

Look closely at the help page I posted the link to.  Your string dates are wrong.

Looks like the date strings are wrong.  Take a close look at this: https://docs.microsoft.com/en-us/sql/t-sql/functions/cast-and-convert-transact-sql?view=sql-server-2017

Definitely started intrinsically for me.  I started playing with a programmable desktop calculator my grandfather bought for his medical lab practice, an HP9810.  I took to it quickly and the...

Well, glad someone decided to reconsider a cursor.

Sounds like a reporting type of database to me, not an OLTP.  Perhaps a star schema may make more sense.  Just another observation.