SQL查询此要求

Question

我有一个带有表sample，surveytype和status的sqlite数据库。所有3个表的主键id被设置为表'Operation'的外键。请参阅中的scema以下图片

我的operation表因此具有值

并以

为样本

和状态

和调查类型为

REQUIRED

我需要实现的是

从操作表中获取状态ID 的信息，并针对所有调查类型显示特定建筑物。

试过

我找到了一种方法，通过程序循环获取所有样本ID和所有调查类型，并获得单独的状态ID

for all sampleid in sample table
{
   for all statustypeid in statustype table
   {  
      select statusid from operation where sampleid = 2 and surveytypeid=1
    }
}

sql single query是否有更好的选项来生成包含所有值的表

注意：使用sqlite，适用于ios app

Answer 1

首先：为什么Operation.StatusID类型为Text，当它填充整数字段的值时？ 可能会询问有关RegionID的相同信息，但由于Region表格未在此处列出，我无法分辨，也许您在该特定情况下需要Text。但将Operation.StatusID作为Text是完全没有道理的，会给你带来性能损失。

然而，有一个老技巧，称为旋转，但它只适用于固定数量的列，在您的情况下 - 调查：

SELECT
  Sample.BuildingID,
  MAX(Sample.BuildingName_EN) BuildingID,
  MAX(CASE WHEN Operation.SurveyTypeID=1 THEN Operation.StatusID ELSE " " END) AS Survey1,
  MAX(CASE WHEN Operation.SurveyTypeID=2 THEN Operation.StatusID ELSE " " END) AS Survey2,
  MAX(CASE WHEN Operation.SurveyTypeID=3 THEN Operation.StatusID ELSE " " END) AS Survey3
FROM Sample,Operation
WHERE Operation.SampleID=Sample.ID
GROUP BY Sample.BuildingID

更新： 为确保此解决方案的可扩展性，您必须在每次使用之前生成此查询，并使用另一个：

SELECT '  SELECT Sample.BuildingID,MAX(Sample.BuildingName_EN) BuildingID,'
UNION ALL
SELECT concat(' MAX(CASE WHEN Operation.SurveyTypeID=',SurveyType.ID,' THEN Operation.StatusID ELSE " " END) AS "',SurveyType.LongName,'",') from SurveyType
UNION ALL
SELECT '0 as dummy FROM Sample,Operation WHERE Operation.SampleID=Sample.ID GROUP BY Sample.BuildingID'

或者，对于Oracle和SQLite：

SELECT '  SELECT Sample.BuildingID,MAX(Sample.BuildingName_EN) BuildingID,'
UNION ALL
SELECT ' MAX(CASE WHEN Operation.SurveyTypeID='||SurveyType.I||' THEN Operation.StatusID ELSE " " END) AS "'||SurveyType.LongName||'",' from SurveyType
UNION ALL
SELECT '0 as dummy FROM Sample,Operation WHERE Operation.SampleID=Sample.ID GROUP BY Sample.BuildingID'

Answer 2

我不讨论模型本身，但有一对多关系 Sample [1] - [*] Operation 。 因此，如果要在SQL行中查询样本的所有操作，则必须编写子选择。 只有当thre是固定的操作量并且我认为它是动态的时候才能这样做。

更常见的方法是与样本条目的复制进行qyery关系并在代码中处理它

SELECT s.building_name, s.building_id, o.statusID 
from sample s, operation o
where s.id = o.sampleid

其他方法是在给定状态的单独查询中选择操作。

SELECT o.statusID 
operation o
where o.sampleid  = 12 

Answer 3

你需要转动数据，不幸的是在mysql中你无法动态地实现这一点。

试试这个：

SELECT
    s.BuildingName_EN as building_name,
    s.ID building_id,
    SUM(CASE WHEN st.LongName = 'Survey1' THEN sa.ID ELSE 0 END) as Survey1,
    SUM(CASE WHEN st.LongName = 'Survey2' THEN sa.ID ELSE 0 END) as Survey2,
    SUM(CASE WHEN st.LongName = 'New Survey 3' THEN sa.ID ELSE 0 END) as 'New Survey 3'
FROM 
    Operation o
LEFT JOIN Sample s
    ON o.SampleID = s.ID 
LEFT JOIN Status sa
    ON o.StatusID = sa.ID 
LEFT JOIN SurveyType st
    ON o.SurveyTypeID = st.ID 
GROUP BY
    s.ID

Answer 4

您希望每种调查类型都有一列。 这是不可能直接实现的，因为SQLite没有透视功能。

您需要执行两个步骤。 首先，获取所有调查类型：

SELECT ID, Longname FROM SurveyType

然后，使用这些值为每个调查类型列构建一个带有一个子查询的查询，如下所示：

SELECT BuildingName_EN AS 'Building Name',
       BuildingID AS 'Building id',
       (SELECT StatusID FROM Operation
        WHERE SampleID = Sample.ID AND SurveyTypeID = 1) AS 'Survey 1',
       (SELECT StatusID FROM Operation
        WHERE SampleID = Sample.ID AND SurveyTypeID = 2) AS 'Survey 2',
       (SELECT StatusID FROM Operation
        WHERE SampleID = Sample.ID AND SurveyTypeID = 3) AS 'New Survey 3'
FROM Sample

Answer 5

For this first you have to join two tables like : Operation and Sample with SurveyType and then pivot the column 'LongName' of SurveyType. We can achieve it dynamically. 

Here is the query...



Select * FROM 
(Select Sample.BuildingName_EN AS 'Building Name', 
        Sample.BuildingID,
        SurveyType.LongName,
        Operation.StatusID 
from SurveyType
Inner Join Operation ON 
    Operation.SurveyTypeID = SurveyType.ID
Inner Join Sample ON
    Operation.SampleID = Sample.ID
    ) P
PIVOT
(
MAX(StatusID)
FOR LongName
IN ([Survey 1],[Survey 2],[New Survey 3])
) AS pvt