IF not EXISTS( SELECT * FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'Refer' AND  COLUMN_NAME = 'ReferDateTime')
begin
	alter table Refer Add	ReferDateTime varchar(20)
end
IF not EXISTS( SELECT * FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'Refer' AND  COLUMN_NAME = 'ViewDateTime')
begin
	alter table Refer Add	ViewDateTime varchar(20)
end
IF not EXISTS( SELECT * FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'Refer' AND  COLUMN_NAME = 'SendDateTime')
begin
	alter table Refer Add	SendDateTime varchar(20)
end