dbo.check_my_date.sql

create FUNCTION dbo.check_my_date (@value varchar(255))
RETURNS datetime2
as
BEGIN
  declare @rt datetime2;

  set @rt = convert(datetime2,'19000101') -- default value

  if @value = '0' -- special case
  begin
    set @rt = convert(datetime2,'00010101')
  end
  else
	begin
    set @rt = try_parse(@value as datetime2)

	--  logic around dates before a certain date
	if try_parse(@value as datetime2) < convert(datetime2,'19000101')
	begin
		set @rt = convert(datetime2,'19000101') 
	end

  end

  return @rt;
END;