Question

Is anybody to know how to enumerate all week’s days in T-SQL, so that we have in the ouput a string like: ‘Sunday, Monday, Tuesday, …’

Answer 1

A straight select that will work with any SET DATEFIRST setting

select
    datename(dw,   6-@@datefirst) + ', ' +
    datename(dw, 1+6-@@datefirst) + ', ' +
    datename(dw, 2+6-@@datefirst) + ', ' +
    datename(dw, 3+6-@@datefirst) + ', ' +
    datename(dw, 4+6-@@datefirst) + ', ' +
    datename(dw, 5+6-@@datefirst) + ', ' +
    datename(dw, 6+6-@@datefirst)

If you don’t care about region (Monday or Sunday as first day of week), then just

select
    datename(dw, 0) + ', ' + datename(dw, 1) + ', ' +
    datename(dw, 2) + ', ' + datename(dw, 3) + ', ' +
    datename(dw, 4) + ', ' + datename(dw, 5) + ', ' +
    datename(dw, 6) + ', '

It will perform much better than going through CTE and will also work in 2000 should you ever need it.