Thanks for clear explanations, but what about the second part of the initial question?

The statement in MSDN, and I quote, is: "... while expressions involving COALESCE with non-null parameters is...

P.S.: ... and "Send Feedback" button directs you to email to sqldocfb@microsoft.com, but when you do, the email is rejected: "The following organization rejected your message: mail.messaging.microsoft.com."

The most complicated...

To opc.three:

> Integers are the default data type SQL Server

... and we know it how?

This is what the question was all about, but googling for something like "sql server default...

Good dtuff, thank you, but I was getting "division by zero" so I wrapped relevant code of proc_FilltblIndexUsageInfo in a CASE:

CASE WHEN dbo.Uf_GetindexSize(si.index_id, so.object_id) != 0 THEN

CAST((user_seeks + user_scans +...