LET vDate = '01.01.2021,02.01.2021,03.01.2021,04.01.2021,05.01.2021';
// Формируем фразу для поля
LET FieldSelectPhrase = '0';
for i = 1 to SubStringCount('$(vDate)',',')
LET FieldSelectPhrase = '$(FieldSelectPhrase)' & '+ if(' & num(SubField('$(vDate)',',',$(i))) & ' >= StartDate AND ' & num(SubField('$(vDate)',',',$(i))) & ' <= EndDate, 1, 0)';
next i;
// Выполняем LOAD запрос
LOAD
StartDate,
EndDate,
$(FieldSelectPhrase) AS IsDateBetween;