Question

我一直试图弄清楚这一点没有成功。我有一个名为Appraisal的表，其中有一列StatusID。我需要计算按StatusId分组的评估数。 Appraisal中的某些记录在StatusID中包含NULL /空值。如果评估师对StatusId = NULL进行评估，最终结果将是0。

鉴定

[AppraisalId] [AppraiserId] [StatusId]
1           11111           1
2           11111           2
3           11111           NULL
4           22222           4
5           22222           NULL
...

AppraisalStatus

[AppraisalStatusId] [AppraisalStatusName]
2                   Assigned
3                   Accepted
6                   Conditionally Declined
7                   Completed
10                  On Hold
11                  Order Not Accepted

评价人

[AppraiserId]
11111
22222

查询：

SELECT 
    AppraisalStatus.AppraisalStatusId, 
    COUNT(ISNULL(Appraisal.StatusId, 0)) AS "number_of_orders"
FROM
    AppraisalStatus
LEFT JOIN 
    Appraisal ON AppraisalStatus.AppraisalStatusId = Appraisal.StatusId
WHERE 
    AppraiserId = :AppraiserId

JSON中的结果

[{
  "AppraisalStatusId": 2,
  "number_of_orders": 1
}, {
  "AppraisalStatusId": 3,
  "number_of_orders": 5
}, {
  "AppraisalStatusId": 7,
  "number_of_orders": 184
}, {
  "AppraisalStatusId": 10,
  "number_of_orders": 2
}]

Answer 1

这是你想要的吗？

SELECT aps.AppraisalStatusId, COUNT(a.StatusId) as number_of_orders
FROM AppraisalStatus aps LEFT JOIN
     Appraisal a
     ON aps.AppraisalStatusId = a.StatusId AND
        a.AppraiserId = :AppraiserId
GROUP BY aps.AppraisalStatusId;

这将为给定的评估师的每个状态返回一行。如果没有匹配的记录，则值为0.

Answer 2

您可以SUM使用COUNT代替GROUP BY。

SELECT 
    AppraisalStatus.AppraisalStatusId, 
    SUM(IIF(Appraisal.StatusId IS NULL, 0, 1)) AS "number_of_orders"
FROM
    AppraisalStatus
LEFT JOIN 
    Appraisal ON AppraisalStatus.AppraisalStatusId = Appraisal.StatusId
WHERE 
    AppraiserId = :AppraiserId
GROUP BY AppraisalStatus.AppraisalStatusId

SQL Server查询COUNT NULL /空值和GROUP BY

2 个答案: