如何在date_trunc中添加整数变量

Question

I want to add my i variable in the date_trunc. My i variable has value 10. This is a piece of my code :

date_trunc('month', now()) - interval 'i  month'

error:

pq: invalid input syntax for type interval: "i  month"

Answer 1

您可以使用算术：

date_trunc('month', now()) - i * interval '1  month'