SQL高級查詢 - 在SELECT子句

Question

我試圖執行以下查詢，但我收到一個運行時錯誤，指出單列彙總子查詢的問題：

"The column is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause." 

線二號下面是一個以上錯誤失敗。我不明白爲什麼這個查詢沒有執行，因爲在第二行中不需要分組，因爲輸出只是count（*），任何線索我需要改變才能使其工作？

SELECT @lessonPlans = COUNT(*) 
, @lessonPlanResources = (SELECT COUNT(*) FROM dbo.LessonPlanResource lpr where lpr.LessonPlanId = a.LessonPlanId) 
FROM 
( 
    SELECT DISTINCT lpt.LessonPlanId 
    FROM dbo.LearningTargetBreakout ltb 
    JOIN dbo.LessonPlanLearningTarget lpt 
     on lpt.LearningTargetId = ltb.LearningTargetId 
    WHERE (CASE 
      WHEN ltb.LearningTargetId = @learningTargetId and @learningTargetId is not null THEN 1 
      WHEN ltb.CategoryId = @categoryId and @categoryId is not null THEN 1 
      WHEN ltb.Grade = @grade and @grade is not null THEN 1 
      WHEN ltb.SubjectId = @subjectId and @subjectId is not null THEN 1 
      ELSE 0 END) = 1 
) a 

[編輯]

使用瑞伯的解決方案的細微變化 - 這裏是修改後的代碼，我結束了使用，這將產生一個排，聚集，這是我後。

SELECT @lessonPlans = ISNULL(COUNT(*), 0) 
     , @lessonPlanResources = ISNULL(SUM(a.ResCount), 0) 
FROM 
( 
    SELECT DISTINCT lpt.LessonPlanId, lpr.ResCount 
    FROM dbo.LearningTargetBreakout ltb 
    JOIN dbo.LessonPlanLearningTarget lpt 
     on lpt.LearningTargetId = ltb.LearningTargetId 
    JOIN (SELECT LessonPlanId, COUNT(*) ResCount FROM dbo.LessonPlanResource lpr GROUP BY LessonPlanId) lpr 
     ON lpr.LessonPlanId = lpt.LessonPlanId   
    WHERE (CASE 
      WHEN ltb.LearningTargetId = @learningTargetId and @learningTargetId is not null THEN 1 
      WHEN ltb.CategoryId = @categoryId and @categoryId is not null THEN 1 
      WHEN ltb.GradeId = @grade and @grade is not null THEN 1 
      WHEN ltb.SubjectId = @subjectId and @subjectId is not null THEN 1 
      ELSE 0 END) = 1 
) a 

Answer 1

我的猜測是，@lessonPlanResources鏈接到LessonPlanId，這不是聚合。

我的解決方案是加入到該子表中，並將返回的列作爲COUNT。

SELECT @lessonPlans = COUNT(*) 
, @lessonPlanResources = SUM(zlpr.reses) 
FROM 
( 
    SELECT DISTINCT lpt.LessonPlanId, zlpr.reses 
    FROM dbo.LearningTargetBreakout ltb 
    JOIN dbo.LessonPlanLearningTarget lpt 
     on lpt.LearningTargetId = ltb.LearningTargetId 
    JOIN (SELECT LessonPlanId, COUNT(*) reses FROM dbo.LessonPlanResource lpr) zlpr 
     ON zlpr.LessonPlanId = lpt.LessonPlanId 
    WHERE (CASE 
      WHEN ltb.LearningTargetId = @learningTargetId and @learningTargetId is not null THEN 1 
      WHEN ltb.CategoryId = @categoryId and @categoryId is not null THEN 1 
      WHEN ltb.Grade = @grade and @grade is not null THEN 1 
      WHEN ltb.SubjectId = @subjectId and @subjectId is not null THEN 1 
      ELSE 0 END) = 1 
) a 

Answer 2

你count(*)是一個聚合函數和@lessonPlanResources表達不是（即使它是一個查詢與COUNT(*)）。因此，表達式必須包含在GROUP BY子句中。

您可以使用公用表表達式（CTE），這也可能有助於提高可讀性。

WITH LPR_CTE as 
    (
    SELECT LessonPlanId, COUNT(*) as LessonPlanResourcesCount 
    FROM dbo.LessonPlanResource 
    GROUP BY LessonPlanId 
    ), 

    LP_CTE(
    SELECT lpt.LessonPlanId, COUNT(*) as LessonPlansCount 
    FROM dbo.LearningTargetBreakout ltb 
    JOIN dbo.LessonPlanLearningTarget lpt 
     on lpt.LearningTargetId = ltb.LearningTargetId 
    WHERE (CASE 
      WHEN ltb.LearningTargetId = @learningTargetId and @learningTargetId is not null THEN 1 
      WHEN ltb.CategoryId = @categoryId and @categoryId is not null THEN 1 
      WHEN ltb.Grade = @grade and @grade is not null THEN 1 
      WHEN ltb.SubjectId = @subjectId and @subjectId is not null THEN 1 
      ELSE 0 END) = 1 
    ) 

SELECT @lessonPlans = LP_CTE.LessonPlansCount 
    , @lessonPlanResources = LPR_CTE.LessonPlanResourcesCount 
FROM LP_CTE 
JOIN LPR_CTE on LP_CTE.LessonPlanId = LPR_CTE.LessonPlanId 

Answer 3

您將需要GROUP BY a.LessonPlanId並根據正是你正在嘗試做可能改變第一COUNT(*)到COUNT(*) OVER()。

但是，這可能會給出多行結果，然後嘗試將其分配給一組標量變量。你想要做什麼是？

Answer 4

的問題是，你正在使用此子查詢分組功能（計數）：SELECT COUNT（*）FROM dbo.LessonPlanResource LPR其中lpr.LessonPlanId = a.LessonPlanId

然而，參考a.LessonPlanId是一個非分組字段。將您的查詢分組，您可以引用該字段。

試試這個：

SELECT @lessonPlans = COUNT(*) 
, @lessonPlanResources = (SELECT COUNT(*) FROM dbo.LessonPlanResource lpr where lpr.LessonPlanId = a.LessonPlanId) 
FROM 
( 
    SELECT DISTINCT lpt.LessonPlanId 
    FROM dbo.LearningTargetBreakout ltb 
    JOIN dbo.LessonPlanLearningTarget lpt 
     on lpt.LearningTargetId = ltb.LearningTargetId 
    WHERE (CASE 
      WHEN ltb.LearningTargetId = @learningTargetId and @learningTargetId is not null THEN 1 
      WHEN ltb.CategoryId = @categoryId and @categoryId is not null THEN 1 
      WHEN ltb.Grade = @grade and @grade is not null THEN 1 
      WHEN ltb.SubjectId = @subjectId and @subjectId is not null THEN 1 
      ELSE 0 END) = 1 
) a 
GROUP BY a.LessonPlanID 

Answer 5

• 刪除從外部選擇計數。
• 在使用COUNT DISTINCT你內心的選擇

---

SELECT 
    @lessonPlans = a.B, 
    @lessonPlanResources = (SELECT COUNT(*) FROM dbo.LessonPlanResource lpr where lpr.LessonPlanId = a.LessonPlanId) 
FROM 
( 
    SELECT COUNT (DISTINCT, lpt.LessonPlanId) AS B 
    FROM dbo.LearningTargetBreakout ltb 
    JOIN dbo.LessonPlanLearningTarget lpt 
     on lpt.LearningTargetId = ltb.LearningTargetId 
    WHERE (CASE 
      WHEN ltb.LearningTargetId = @learningTargetId and @learningTargetId is not null THEN 1 
      WHEN ltb.CategoryId = @categoryId and @categoryId is not null THEN 1 
      WHEN ltb.Grade = @grade and @grade is not null THEN 1 
      WHEN ltb.SubjectId = @subjectId and @subjectId is not null THEN 1 
      ELSE 0 END) = 1 
) a