monetdb中的日期查询？

Question

我可以进行以下查询

select (current_date-interval '1' day) ,a,b from (select '1' as a, 2 as b) as t2;

但是我无法将变量放在'1'的位置。 我尝试了以下方法但没有成功

select (current_date-interval b day) ,a,b from (select '1' as a, 2 as b) as t2;
select (current_date-interval a day) ,a,b from (select '1' as a, 2 as b) as t2;

我也尝试过施法，但仍然没有结果。

Answer 1

我找到了解决方法：

select (current_date-interval 1 day*b) ,a,b from (select '1' as a, 2 as b) as t2;
select (current_date-interval 1 day*cast(a as int)) ,a,b from (select '1' as a, 2 as b) as t2;

所以回答这个问题：）