Sql （按类别分类和分组） 使用CTE选择具有类别和最小百分比的单独条件检查的数据 使用UNION仅获取不同的记录作为最终输出 让我先告诉你几件事，我的代码是一个，但那一次我只有一个表，而不是三个表。所有信息都存储在一个表中。在DB中进行更改后，我不知道如何在q

（按类别分类和分组）

使用CTE选择具有类别和最小百分比的单独条件检查的数据

使用UNION仅获取不同的记录作为最终输出

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让我先告诉你几件事，我的代码是一个，但那一次我只有一个表，而不是三个表。所有信息都存储在一个表中。在DB中进行更改后，我不知道如何在queryYou说您编写了所有代码，但不知道如何连接这三个表并重用这些代码？我尝试使用连接，但没有得到任何结果。。。有人在这方面帮我Raj你能帮我吗？你说“什么都没得到”是什么意思？你有没有试着加入桌子<代码>从表1中选择*作为t1内部联接表2作为t1上的t2。RollNo=t2.id内部联接表3作为t2上的t3.id=t3.id我想要查询中的确切学生人数。例如，我想要sc类别的5名学生和st类别的10名学生，这在你的查询中是如何实现的..我将感谢你的帮助..我想在工作查询中使用join。。不仅仅是我提出了这个问题sumbody在这方面帮助了我你如何决定你需要选择5个或10个学生？最高百分比？如果它们中的任何一个具有相同的百分比，您将需要添加某种附加类型。那会是什么呢？如果其中任何一个有相同的百分比，那么我们需要根据类别对它们进行排序。如果两名学生（1名来自SC，1名来自OBC）的比例相同，则优先选择i OBC学生。

|  Roll No   | Applicant Name|   Gender   | Category   | Father's Name  |
|------------|---------------|------------|------------|----------------|
|     001    |          A    |          M |      SC    |      as        |
|     002    |          B    |          F |      ST    |      hg        |
|     003    |          C    |          F |      ST    |      yj        |
|     004    |          D    |          M |      OBC   |      uy        |
|     005    |          E    |          F |      SC    |      bn        |
|     006    |          F    |          M |      OBC   |      kl        |
|     007    |          E    |          F |      Gen   |      bn        |
|     008    |          F    |          M |      OBC   |      vg        |
|     009    |          E    |          F |      Gen   |      gh        |
|     010    |          F    |          M |      SC    |      we        |
|------------|---------------|------------|------------|----------------|

|     ID     |    Semester   |   Major    | Applied Course|
|------------|---------------|------------|---------------|
|     001    |          1    |    English |      B.A      |
|     002    |          1    |    English |      B.A      |
|     003    |          1    |    History |      B.A      |
|     004    |          1    |    botany  |      B.Sc     |
|     005    |          1    |    Hindi   |      B.A      |
|     006    |          1    |    History |      B.A      |
|     007    |          1    |    Maths   |      B.A      |
|     008    |          1    |    Hindi   |      B.A      |
|     009    |          1    |    History |      B.A      |
|     010    |          1    | Pol.Science|      B.A      |
|------------|---------------|------------|---------------|

|     ID     |Plus2Percentage|
|------------|---------------|
|     001    |         60    |
|     002    |         65    |
|     003    |         70    |
|     004    |         73    |
|     005    |         87    |
|     006    |         91    |
|     007    |         59    |
|     008    |         78    |
|     009    |         88    |
|     010    |         57    |
|------------|---------------|-

|   Roll No  |Plus2Percentage|  Category |
|------------|---------------|-----------|
|     005    |         87    |    SC     |
|     001    |         60    |    SC     |
|     003    |         70    |    ST     |
|     002    |         65    |    ST     |
|     006    |         91    |   OBC     |
|     009    |         88    |   Gen     |
|     008    |         78    |   OBC     |
|------------|---------------|-----------|

   WITH PRIMARY_CHOICE AS ( 
    SELECT 
        RollNo, 
        ApplicantName, 
        FatherName, 
        Gender, 
        Major,
        Category, 
        Plus2Percentage 
    FROM ( 
        SELECT 
            RollNo, 
            ApplicantName, 
            FatherName, 
            Gender, 
            Semester, 
            Major, 
            AppliedCourse, 
            Category, 
            Plus2Percentage, 
            row_number() over (partition by Category, Semester, Major, AppliedCourse order by Plus2Percentage desc) as rn 
        FROM [College Management System].[dbo].[ApplicantPersonalDetail]
    ) as T 
    WHERE 
        rn <= CASE 
                WHEN Category='SC' AND Semester='1'  AND AppliedCourse= 'B.A' AND Plus2Percentage >= '60' THEN '2'
                WHEN Category='ST' AND Semester= '1'  AND AppliedCourse= 'B.A' AND Plus2Percentage >= '65'THEN '2'
                WHEN Category='OBC' AND Semester= '1'  AND AppliedCourse= 'B.A' AND Plus2Percentage >= '60' THEN '1'
                ELSE 0 
            END 
) 
SELECT 
    RollNo, 
    ApplicantName, 
    FatherName, 
    Gender, 
    Major, 
    Category, 
    Plus2Percentage 
FROM PRIMARY_CHOICE 

UNION ALL

SELECT 
    RollNo, 
    ApplicantName, 
    FatherName, 
    Gender, 
    Major, 
    Category, 
    Plus2Percentage 
FROM ( 
    SELECT 
        RollNo, 
        ApplicantName, 
        FatherName, 
        Gender, 
        Semester, 
        Major, 
        AppliedCourse, 
        Category, 
        Plus2Percentage, 
        row_number() over (partition by Semester, Major1, AppliedCourse  order by Plus2Percentage desc) as rn  
    FROM [College Management System].[dbo].[ApplicantPersonalDetail] x 
    WHERE NOT EXISTS (
        select 1 from primary_choice y  
        where x.RollNo = y.RollNo
    ) 
) AS T2  
WHERE 
    rn <= 2 
    AND Semester = @semester 
    AND AppliedCourse = 'B.A' 
    AND Plus2Percentage >= 70 
order by Plus2Percentage desc

SELECT RollNo, Plus2Percentage, Category 
FROM TABLE1 a
INNER JOIN Table3 b on a.rollno=b.id
WHERE a.category='SC' and b.Plus2Percentage>=60

CREATE PROCEDURE usp_SelectCategorywiseData 
AS 
BEGIN 
SET NOCOUNT ON;

    DECLARE  @tbl_LIST TABLE (RollNo int, [Plus2Percentage] int, Category varchar(10));

    WITH CTE AS 
    (
      SELECT A.RollNo, P.Percentage AS [Plus2Percentage], A.Category
      , row_number() OVER (PARTITION BY A.Category ORDER BY P.Percentage DESC) AS Rank 
      FROM APPLICANT A INNER JOIN  Plus2Percentage P ON A.RollNo = P.ID
    )


    INSERT INTO @tbl_LIST
    SELECT RollNo, Plus2Percentage as [Plus2Percentage], Category 
    FROM CTE 
    WHERE rank <= 
    CASE 
        WHEN Category='SC' AND [Plus2Percentage] >= '60' THEN '2' 
        WHEN Category='ST' AND [Plus2Percentage] >= '60' THEN '2' 
        WHEN Category='OBC' AND [Plus2Percentage] >= '55' THEN '1' 
    ELSE 0 
    End


    INSERT INTO @tbl_LIST
    SELECT TOP 2 A.RollNo, P.Percentage as [Plus2Percentage], A.Category 
    FROM APPLICANT A INNER JOIN  Plus2Percentage P ON A.RollNo = P.ID
    WHERE Percentage > 70 and RollNo NOT IN (SELECT RollNo FROM @tbl_LIST) ORDER BY P.Percentage DESC

    SELECT * FROM @tbl_LIST 
END