使用SQL顯示基於記錄計數的結果

Question

我有一個名為schoolDB的數據庫和2個數據庫表，

student和education

創建學生表：

USE [schoolDB]
GO

/****** Object:  Table [dbo].[tblStudent]    Script Date: 09/22/2013 17:30:11 ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

SET ANSI_PADDING ON
GO

CREATE TABLE [dbo].[tblStudent](
    [STUDENTNUMBER] [varchar](50) NOT NULL,
    [STUDENTNAME] [varchar](50) NULL,
    [EDUCATIONID] [varchar](50) NULL,
 CONSTRAINT [PK_tblStudent] PRIMARY KEY CLUSTERED 
(
    [STUDENTNUMBER] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

SET ANSI_PADDING OFF
GO

創建教育表：

USE [schoolDB]
GO

/****** Object:  Table [dbo].[tblEducation]    Script Date: 09/22/2013 17:31:30 ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

SET ANSI_PADDING ON
GO

CREATE TABLE [dbo].[tblEducation](
    [EDUCATIONID] [varchar](50) NOT NULL,
    [STUDENTNUMBER] [varchar](50) NULL,
    [INSTITUTIONNAME] [varchar](50) NULL,
    [COURSENAME] [varchar](50) NULL,
    [GRADE] [varchar](50) NULL,
    [YEAROFLEAVING] [varchar](50) NULL
) ON [PRIMARY]

GO

SET ANSI_PADDING OFF
GO

以下是數據的屏幕截圖：

我希望能夠找到每個去過一所名為Secondary School的機構名稱的人，並且他的另一個教育記錄是like biol like的課程名稱。 不僅限於生物學，我想找到所有的科學，所以我需要提出多個相似的陳述。

我試過這個：

SELECT COUNT(*) AS 'Our Students', 
       DTOurStudents.STUDENTNAME 
FROM   (SELECT TOP 2 TBLSTUDENT.STUDENTNUMBER, 
                     TBLSTUDENT.STUDENTNAME, 
                     TBLEDUCATION.INSTITUTIONNAME, 
                     TBLEDUCATION.COURSENAME 
        FROM   TBLEDUCATION 
               INNER JOIN TBLSTUDENT 
                       ON TBLEDUCATION.STUDENTNUMBER = TBLSTUDENT.STUDENTNUMBER 
        WHERE  TBLEDUCATION.INSTITUTIONNAME LIKE '%Secondary School%') 
       DTOurStudents 
GROUP  BY DTOurStudents.STUDENTNAME

SQL FIDDLE： http ：//sqlfiddle.com/#！3/666f8/2

Answer 1

這將為您提供一份學生名單和大學課程（每所大學），通過加入機構表自己。

SELECT
  STUDENTNUMBER,
  SCHOOL_NAME,
  COLLEGE_NAME,
  count(*) as COLLEGE_COURSES
FROM (
  SELECT    
    school.STUDENTNUMBER,
    school.INSTITUTIONNAME AS SCHOOL_NAME,
    college.INSTITUTIONNAME AS COLLEGE_NAME
  FROM dbo.tblEducation as school
  INNER JOIN dbo.tblEducation as college ON school.STUDENTNUMBER = college.STUDENTNUMBER
  WHERE school.INSTITUTIONNAME = 'Secondary School'
    AND college.INSTITUTIONNAME <> 'Secondary School'
    AND (college.COURSENAME like 'biol%'
         OR college.COURSENAME like 'math%'
         OR college.COURSENAME like 'etc%')
) AS c
GROUP BY STUDENTNUMBER, SCHOOL_NAME, COLLEGE_NAME

如果你想要大學的coursename那么你可以在內部查詢中返回。 但由於每個大學課程只有一個記錄，外部select和group by將是多余的。

SELECT  
  school.STUDENTNUMBER,
  school.INSTITUTIONNAME AS SCHOOL_NAME,
  college.INSTITUTIONNAME AS COLLEGE_NAME,
  college.COURSENAME
FROM dbo.tblEducation as school
INNER JOIN dbo.tblEducation as college ON school.STUDENTNUMBER = college.STUDENTNUMBER
WHERE   school.INSTITUTIONNAME = 'Secondary School'
  AND college.INSTITUTIONNAME <> 'Secondary School'
  AND  (college.COURSENAME like 'biol%'
          OR college.COURSENAME like 'math%'
          OR college.COURSENAME like 'etc%'

Answer 2

一個簡單的答案。

1. 我選擇所有感興趣的行（即'中學'或通過coursename）。
2. 我計算每個學生的行數。
3. 我過濾以保持至少有2行的學生。
4. 我在ORDER BY使用表達式來確保中學首先出現。

您的問題不明確的是當有超過2行時會發生什么。 在這種情況下，它們都會顯示，但查詢很容易調整（在rn <= 2上添加row_number和filter）。

小提琴： http ：//sqlfiddle.com/#！3/666f8/89/0

WITH cte as (
  SELECT  
    STUDENTNUMBER, 
    COURSENAME, 
    INSTITUTIONNAME,
    COUNT(*) OVER (PARTITION BY STUDENTNUMBER) AS RecordCount
  FROM tblEducation
  WHERE INSTITUTIONNAME = 'Secondary School'
     OR COURSENAME like 'biol%'
     OR COURSENAME like 'math%'
     OR COURSENAME like 'etc%'
)
select *
from cte
where RecordCount >= 2
order by 
  studentnumber, 
  case when institutionname = 'Secondary School' then 1 else 2 end

編輯

評論正確地指出查詢不會檢查是否至少有一所中學和另一項教育。 可能有兩所中學，或根本沒有中學！

可以使用下面稍微復雜的查詢來處理這些情況：

WITH cte as (
  SELECT  
    STUDENTNUMBER, 
    COURSENAME, 
    INSTITUTIONNAME,
    SUM(CASE INSTITUTIONNAME WHEN 'Secondary School' THEN 1 END) 
      OVER (PARTITION BY STUDENTNUMBER) AS SecondarySchoolCount,
    SUM(CASE WHEN INSTITUTIONNAME <> 'Secondary School' 
              AND COURSENAME LIKE 'biol%' 
             THEN 1 END) 
      OVER (PARTITION BY STUDENTNUMBER) AS CourseCount
  FROM tblEducation
  WHERE INSTITUTIONNAME = 'Secondary School'
     OR COURSENAME like 'biol%'
     OR COURSENAME like 'math%'
     OR COURSENAME like 'etc%'
)
select *
from cte
where SecondarySchoolCount >= 1 AND CourseCount >= 1
order by 
  studentnumber, 
  case when institutionname = 'Secondary School' then 1 else 2 end

Answer 3

如果要顯示兩個行，可以使用此查詢：

select a.*    
from tblEducation as a
where
    exists (
        select *  
        from tblEducation as t
        where t.INSTITUTIONNAME = 'Secondary School' and t.STUDENTNUMBER = a.STUDENTNUMBER  
    ) and
    exists (
        select *
        from tblEducation as t
        where t.INSTITUTIONNAME <> 'Secondary School' and t.STUDENTNUMBER = a.STUDENTNUMBER  
    )

或者你可以這樣做：

with cte as (
    select
        a.STUDENTNUMBER
    from tblEducation as a
    group by
        a.STUDENTNUMBER,
        case when a.INSTITUTIONNAME = 'Secondary School' then 1 else 0 end
)
select a.*
from tblEducation as a
where
    a.STUDENTNUMBER in (
         select t.STUDENTNUMBER
         from cte as t group by t.STUDENTNUMBER
         having count(*) > 1
    )

實際上，如果至少有一行包含INSTITUTIONNAME = 'Secondary School'且至少有一行包含INSTITUTIONNAME <> 'Secondary School' ，則這兩個查詢都會顯示STUDENTNUMBER的所有行

sql小提琴演示

Answer 4

嘗試這個

WITH CTE AS
(
SELECT E.STUDENTNUMBER
FROM (SELECT * FROM TBLEDUCATION WHERE INSTITUTIONNAME LIKE '%Secondary School%') E
INNER JOIN (SELECT * FROM TBLEDUCATION WHERE  INSTITUTIONNAME NOT LIKE '%Secondary School%' AND COURSENAME LIKE '%biol%') E1
ON E.STUDENTNUMBER=E1.STUDENTNUMBER
)

SELECT *
FROM   TBLSTUDENT S
INNER JOIN TBLEDUCATION E
ON S.STUDENTNUMBER = E.STUDENTNUMBER
WHERE S.STUDENTNUMBER IN (SELECT STUDENTNUMBER FROM CTE)

Answer 5

SELECT DISTINCT s.STUDENTNUMBER
FROM tblStudent s
INNER JOIN tblEducation e
ON (s.studentnumber = e.studentnumber and (
    e.institutionname = 'Secondary School'
    or e.coursename like '%biol%' 
    OR e.coursename like '%math%'
))

應該管用？

Answer 6

以下示例在相關子查詢上使用EXISTS運算符，該子查詢具有連接兩個查詢

SELECT *
FROM dbo.tblEducation t
WHERE EXISTS (SELECT 1
              FROM (SELECT e.STUDENTNUMBER
                    FROM dbo.tblEducation e
                    WHERE e.INSTITUTIONNAME = 'Secondary School'
              ) x JOIN (SELECT e2.STUDENTNUMBER 
                        FROM dbo.tblEducation e2
                        WHERE e2.INSTITUTIONNAME != 'Secondary School'
                        ) x2 ON x.STUDENTNUMBER = x2.STUDENTNUMBER
              WHERE x.STUDENTNUMBER =  t.STUDENTNUMBER
              )

請參閱SQLFiddle演示

要么

SELECT *
FROM tblEducation t3
WHERE EXISTS(SELECT t.STUDENTNUMBER
             FROM tblEducation t
             WHERE t.INSTITUTIONNAME LIKE 'Secondary School'
               AND EXISTS(SELECT 1
                          FROM tblEducation t2
                          WHERE t.STUDENTNUMBER = t2.STUDENTNUMBER
                            AND t2.INSTITUTIONNAME != t.INSTITUTIONNAME
                          )
               AND t3.STUDENTNUMBER = t.STUDENTNUMBER
             )