Auto set Time in Datetime field

[Espegg]

I would when a column as a specific value to set in a datetime column the time,
example:
- when in column Color there is the value yellow, in the column Calendar the datetime must have the day customizable but the time must be "09:00:00"

How could I proceed?

[AleksiAlkio · Accepted solution]

You can either use the existing DateTime field with the initial value something like..
TODAY()&" "&
SWITCH([Color],
"Yellow","09:00:00",
"Blue","10:00:00",
"12:00:00"
)

If you want to select the date individually, add an additional date column and then use that date with your existing DateTime column in a same way.