Expose all the functions in DateTime and the concepts defined
here
function categories
field access: all functions in the DateTime are available as sql functions.
The first argument is the
DateTime object on which the function is to be applied.
construction: functions are available to convert a String or a epoch value to DateTime
comparison: functions available to compare dates (=, <, <=, >, >=), also compare
against now.
arithmetic: functions available to add/subtract Period from dates.
Expose all the functions in DateTime and the concepts defined here
function categories