Sql 我需要帮助显示零字段

在这个查询中，我对上周创建的工单进行计数，并按wotype2显示计数。如果前一周的wotype2为零，我需要wotype2出现在我的结果中。有没有办法解决这个问题

-- Retrieve Last Week's New Work Orders.

DECLARE @TodayDayOfWeek INT
DECLARE @EndOfPrevWeek DateTime
DECLARE @StartOfPrevWeek DateTime

 --get number of a current day (1-Monday, 2-Tuesday... 7-Sunday)
SET @TodayDayOfWeek = datepart(dw, GetDate())
 --get the last day of the previous week (last Sunday)
SET @EndOfPrevWeek = DATEADD(dd, -@TodayDayOfWeek, GetDate())
 --get the first day of the previous week (the Monday before last)
SET @StartOfPrevWeek = DATEADD(dd, -(@TodayDayOfWeek+6), GetDate())


SELECT wotype2 as WOType, COUNT(*) as NewWOsLastWeek
FROM tasks
WHERE ((OpenDATE BETWEEN 
    CONVERT(VARCHAR, @StartOfPrevWeek,7)  AND
    CONVERT(VARCHAR, @EndOfPrevWeek+1,7)) AND
    (TYPE = 'Information Systems')        AND
    (RESPONS != 'ADMIN'))
group by wotype2
order by wotype2

---

您可能需要对包含wotype2所有可能值的表进行外部联接（例如左外部联接）

如果有这样一个表，假设它被命名为wotype2s，那么SQL将是：

SELECT wotype2s.wotype2 as WOType, COUNT(*) as NewWOsLastWeek
FROM wotype2s left outer join tasks on wotype2s.wotype2 = tasks.wotype2
WHERE ((OpenDATE BETWEEN 
    CONVERT(VARCHAR, @StartOfPrevWeek,7)  AND
    CONVERT(VARCHAR, @EndOfPrevWeek+1,7)) AND
    (TYPE = 'Information Systems')        AND
    (RESPONS != 'ADMIN'))
group by wotype2s.wotype2
order by wotype2s.wotype2

或者，如果没有这样的表格

SELECT wotype2s.wotype2 as WOType, COUNT(*) as NewWOsLastWeek
FROM (select distinct wotype2 from tasks) wotype2s
  left outer join tasks on wotype2s.wotype2 = tasks.wotype2
WHERE ((OpenDATE BETWEEN 
    CONVERT(VARCHAR, @StartOfPrevWeek,7)  AND
    CONVERT(VARCHAR, @EndOfPrevWeek+1,7)) AND
    (TYPE = 'Information Systems')        AND
    (RESPONS != 'ADMIN'))
group by wotype2s.wotype2
order by wotype2s.wotype2

wotype2是真的为零还是为空？