Do I need a comma when I want to write "Good morning John"? [duplicate]
Solution 1:
Definitely include the comma. 'Good morning' is the declarative statement, the core of the sentence fragment. 'John' is a qualifier, a separate add-on that clarifies who speaker is directing statement to. Compare: "Good morning, whoever you are."
Without a comma, the phrase would means something along the lines of 'John of good mornings'. (Some people might like to be greeted that way!) The 'good morning' would be an adjectival phrase attached to 'John' as the noun.