从上个月的sql中选择数据

I have this code to select from my database data from current month:

SELECT * FROM daily_reports
WHERE username = '$username' and MONTH(date) = MONTH(Now())
order by date DESC

And now i want to display data from last month.

column date is type date

This should work:-

SELECT *
 FROM daily_reports 
WHERE username = '$username' 
and MONTH(date) = MONTH(DATE_ADD(Now(), INTERVAL -1 MONTH))
 order by date DESC

SELECT 
  * 
FROM
  daily_reports 
WHERE username = '$username' 
  AND dateColumn BETWEEN SUBDATE(CURDATE(), INTERVAL 1 MONTH) AND NOW();
ORDER BY DATE DESC 

Try this

SELECT * FROM daily_reports 
WHERE username = '$username' 
and MONTH(date) = MONTH(DATE_ADD(Now(), INTERVAL -1 MONTH)) order by date DESC

You can do many operations on dates, as shown in the fine manual.

In your case, perhaps the DATE_SUB function would be clearest:

SELECT * FROM daily_reports
WHERE username = '$username' AND MONTH(date) = MONTH(DATE_SUB(Now(), INTERVAL 1 MONTH)
ORDER BY date DESC

date BETWEEN date_format
(NOW() - INTERVAL 1 MONTH, '%Y-%m-01') 
AND last_day(NOW() - INTERVAL 1 MONTH)