从日期访问数据库查询以使用月份

Question

I have the following table schema in acess (2007).

Date eventDate bit(boolean) lunch, bit(boolean) snacks, bit(boolean) Tea,

I would like to have a single query that gives count of luch, snacks and tea (each as a column) for a given month (using the eventdate).

Thanks for help.

Answer 1

In Access, True is -1 and False is 0. So you can use the absolute value of the sum of those values to indicate how many were True.

SELECT Abs(Sum(lunch)) AS SumofLunch, Abs(Sum(snacks)) AS SumofSnacks, Abs(Sum(Tea)) AS SumofTea
FROM YourTable
WHERE eventDate >= #2009/08/01# And eventDate < #2009/09/01#;

Answer 2

Try:

SELECT SUM(ABS(lunch)) AS lunchCount, SUM(ABS(snacks)) AS snackCount, SUM(ABS(tea)) AS teaCount
FROM <TableName>
WHERE eventDate >= #1/1/2009# AND eventDate < #2/1/2009#

Answer 3

I'd attack this in access using IIF statements (think like CASE statements in other databases). IIF in Access returns a value when the specified condition is true (after the first comma) or another value if it evaluates to false (after the second comma). Because you are using booleans, checking for a true condition and rolling up via an aggregate sum will do the trick for you.

SELECT Month(EventDate) AS TheMonth, Year(EventDate) AS TheYear, 
SUM(IIF(Lunch, 1, 0)) AS LunchCount,
SUM(IIF(Snacks, 1, 0)) AS SnackCount,
SUM(IIF(Tea, 1, 0)) AS TeaCount
FROM YourTable
GROUP BY Month(EventDate), Year(EventDate)
ORDER BY Month(EventDate), Year(EventDate)

The above query of course returns counts for all months and years however you could easily key in on a date range like below if need be.

SELECT Month(EventDate) AS TheMonth, Year(EventDate) AS TheYear, 
SUM(IIF(Lunch, 1, 0)) AS LunchCount,
SUM(IIF(Snacks, 1, 0)) AS SnackCount,
SUM(IIF(Tea, 1, 0)) AS TeaCount
FROM YourTable
WHERE EventDate BETWEEN #1/1/2009# AND #1/31/2009#
GROUP BY Month(EventDate), Year(EventDate)
ORDER BY Month(EventDate), Year(EventDate)