Steps to repro:
Result:
In column definition datetime is not displayed bold as all the others SQL keywords.

I confirm in versions:
Notepad3 (64-bit) v5.19.108.1602
Notepad3 (64-bit) v5.19.109.1603 Dev_Test_2

It's seems to me a "bug" in "Scintilla SQL Lexer" (also reproducible with "SciTE.415").
I have open an issue in "Scintilla Support".
PS: Notepad++ highlights "datetime" but MS Visual Studio Editor "No". 馃槙
The keyword "datetime" is added.
Feel free to test the beta version: "Notepad3Portable_5.19.423.257_MUI_dev" or higher.
See "Notepad3 beta-channel access #1129" or download it here Notepad3Portable.
Most helpful comment
The keyword "datetime" is added.
Feel free to test the beta version: "Notepad3Portable_5.19.423.257_MUI_dev" or higher.
See "Notepad3 beta-channel access #1129" or download it here Notepad3Portable.