在MYSQLI where子句中使用日期

Question

I have a column in my table called date, and I'm trying to get the maximum date, and the minimum date, before subtracting the minimum date from the maximum date to get the seconds in between them. Then I use the seconds to limit whether I want the row to be shown or not. The problem is that I think I did this part wrong, and nothing is being selected even though it prints out date3 is bigger than 0, when not using the where clause.

SELECT min(date) as date1, max(date) as date2, 
(max(time)-min(time)) as date3 
FROM tableName where date3 > 0;

Answer 1

You cannot reference field aliases in WHERE clauses (unless they are from subqueries in the FROM); instead use HAVING .

Also, I don't think date3 is going to be the number of seconds.

Also2, without a GROUP BY, you are either going to show one row or none.