SQL Server COUNT() 似乎忽略了 WHERE

Question

我正在尝试设置一个 SQL Server 查询，该查询列出在会议活动期间注册参观的人数，然后显示总和。这是我即将接近的 SQL 代码，但它忽略了总计（但不是单个总计）的 WHERE 子句：

SELECT     SiteTour, COUNT(SiteTour) AS count
FROM       tblConference
WHERE      (RegistrationType NOT LIKE 'cancellation')
GROUP BY   SiteTour
UNION ALL
SELECT     'TOTAL' AS SiteTour, COUNT(SiteTour) AS Expr1
FROM       tblConference AS tblConference_1

这是它正在生产的东西：

         0
Tour1   22
Tour2   30
Tour3   30
----------
TOTAL   83

（Tour1 计数 22 是正确的，因为有一个 RegistrationType 取消。但是，83 的总数应该是 82。）

另外，我得到了一个初始行，我猜是基于对 NULL 的计数，显示为 0。有什么方法可以防止这种情况发生？

请帮我纠正这个问题。谢谢你。

Answer 1

您需要在联合选择中添加相同的 where 子句。

SELECT     SiteTour, COUNT(SiteTour) AS count
FROM       tblConference
WHERE      (RegistrationType NOT LIKE 'cancellation')
GROUP BY   SiteTour
UNION ALL
SELECT     'TOTAL' AS SiteTour, COUNT(tblConference_1.SiteTour) AS Expr1
FROM       tblConference AS tblConference_1
WHERE      (tblConference_1.RegistrationType NOT LIKE 'cancellation')

Answer 2

你应该避免做COUNT两次。

;WITH Counts AS
(
    SELECT     SiteTour, COUNT(SiteTour) AS count
    FROM       tblConference
    WHERE      RegistrationType <> 'cancellation' AND SiteTour IS NOT NULL
    GROUP BY   SiteTour
),
Totals AS
(
    SELECT
        C.SiteTour,
        C.count
    FROM
        Counts AS C
    UNION ALL
    SELECT     
        'TOTAL' AS SiteTour, 
        SUM(C.count) AS count
    FROM
        Counts AS C
)
SELECT
    T.SiteTour,
    T.Count
FROM
    Totals AS T
ORDER BY
    CASE 
        WHEN T.SiteTour <> 'TOTAL' THEN 1
        ELSE 2 END,
    T.SiteTour

这样你所有的过滤器也只写一次。