Question

I have the following structure on SQLFiddle that has been created by others who helped me (Using two columns in a PIVOT):

CREATE TABLE Project (
  Id int,
  Name VARCHAR(50),
  CONSTRAINT PK_Project PRIMARY KEY (Id));


CREATE TABLE [User] (
  Id int,
  Name VARCHAR(50),
  Register int,
  CONSTRAINT PK_User PRIMARY KEY (Id));

CREATE TABLE ProjectMember (
  Project_Id int,
  User_Id int, 
  MemberType tinyint,
  CONSTRAINT PK_ProjectMember PRIMARY KEY(Project_Id, User_Id),
  CONSTRAINT FK_ProjectMember_Project FOREIGN KEY(Project_Id) REFERENCES Project(Id),
  CONSTRAINT FK_ProjectMember_User FOREIGN KEY(User_Id) REFERENCES [User](Id));



 INSERT INTO Project(Id, Name) VALUES(1, 'Project 1');
 INSERT INTO Project(Id, Name) VALUES(2, 'Project 2');
 INSERT INTO Project(Id, Name) VALUES(3, 'Project 3');
 INSERT INTO Project(Id, Name) VALUES(4, 'Project 4');
 INSERT INTO Project(Id, Name) VALUES(5, 'Project 5');
 INSERT INTO Project(Id, Name) VALUES(6, 'Project 6');
 INSERT INTO Project(Id, Name) VALUES(7, 'Project 7');


 INSERT INTO [User](Id, Name, Register) VALUES(1, 'User 1', 23498374);
 INSERT INTO [User](Id, Name, Register) VALUES(2, 'User 2', 96849887);
 INSERT INTO [User](Id, Name, Register) VALUES(3, 'User 3', 6546884);
 INSERT INTO [User](Id, Name, Register) VALUES(4, 'User 4', 8489848);
 INSERT INTO [User](Id, Name, Register) VALUES(5, 'User 5', 4684854);
 INSERT INTO [User](Id, Name, Register) VALUES(6, 'User 6', 4849888);
 INSERT INTO [User](Id, Name, Register) VALUES(7, 'User 7', 84884446);
 INSERT INTO [User](Id, Name, Register) VALUES(8, 'User 8', 77554454);
 INSERT INTO [User](Id, Name, Register) VALUES(9, 'User 9', 77853997);

 INSERT INTO ProjectMember(Project_Id, User_Id, MemberType) VALUES(1, 1, 0);
 INSERT INTO ProjectMember(Project_Id, User_Id, MemberType) VALUES(1, 2, 1);
 INSERT INTO ProjectMember(Project_Id, User_Id, MemberType) VALUES(1, 3, 2);
 INSERT INTO ProjectMember(Project_Id, User_Id, MemberType) VALUES(1, 4, 2);
 INSERT INTO ProjectMember(Project_Id, User_Id, MemberType) VALUES(1, 5, 2);
 INSERT INTO ProjectMember(Project_Id, User_Id, MemberType) VALUES(3, 6, 0);
 INSERT INTO ProjectMember(Project_Id, User_Id, MemberType) VALUES(3, 5, 1);
 INSERT INTO ProjectMember(Project_Id, User_Id, MemberType) VALUES(4, 3, 0);
 INSERT INTO ProjectMember(Project_Id, User_Id, MemberType) VALUES(4, 4, 1);
 INSERT INTO ProjectMember(Project_Id, User_Id, MemberType) VALUES(4, 5, 2);

 INSERT INTO ProjectMember(Project_Id, User_Id, MemberType) VALUES(5, 7, 0);

 INSERT INTO ProjectMember(Project_Id, User_Id, MemberType) VALUES(6, 8, 1);

I have a new requirement from my client. He needs a filter to return all projects that have a MemberType = 2 and a specific User.Id, but the returned values doesn't need to include these values.

Example:

With this SQL statement:

SELECT  
    ProjectID              = P.Id, 
    ProjectName            = P.Name, 
    [UserType0 (Name)]     = MAX(CASE WHEN MemberType = 0 THEN u.Name END),
    [UserType0 (Register)] = MAX(CASE WHEN MemberType = 0 THEN Register END), 
    [UserType1 (Name)]     = MAX(CASE WHEN MemberType = 1 THEN u.Name END),
    (CASE WHEN MemberType = 2 THEN u.Name END) as [UserType2]
FROM Project AS P
LEFT JOIN ProjectMember AS PM ON P.Id = PM.Project_Id
LEFT JOIN [User] AS U ON PM.User_Id = U.Id 
GROUP BY P.Id, P.Name, PM.MemberType, U.Name

I get this value:

| ProjectID | ProjectName | UserType0 (Name) | UserType0 (Register) | UserType1 (Name) | UserType2 |
|-----------|-------------|------------------|----------------------|------------------|-----------|
|         1 |   Project 1 |           User 1 |             23498374 |           (null) |    (null) |
|         1 |   Project 1 |           (null) |               (null) |           User 2 |    (null) |
|         1 |   Project 1 |           (null) |               (null) |           (null) |    User 3 |
|         1 |   Project 1 |           (null) |               (null) |           (null) |    User 4 |
|         1 |   Project 1 |           (null) |               (null) |           (null) |    User 5 |
|         2 |   Project 2 |           (null) |               (null) |           (null) |    (null) |
|         3 |   Project 3 |           User 6 |              4849888 |           (null) |    (null) |
|         3 |   Project 3 |           (null) |               (null) |           User 5 |    (null) |
|         4 |   Project 4 |           User 3 |              6546884 |           (null) |    (null) |
|         4 |   Project 4 |           (null) |               (null) |           User 4 |    (null) |
|         4 |   Project 4 |           (null) |               (null) |           (null) |    User 5 |
|         5 |   Project 5 |           User 7 |             84884446 |           (null) |    (null) |
|         6 |   Project 6 |           (null) |               (null) |           User 8 |    (null) |
|         7 |   Project 7 |           (null) |               (null) |           (null) |    (null) |

But what I need is to return a single row per project that contains a user with a specific ID and MemberType = 2. How can I add this filter without changing the results like specified on Using two columns in a PIVOT?

Answer 1

以下是我在上述评论中发布的代码：

DECLARE @USerId int;
SET @UserId = NULL;

SELECT  
    ProjectID              = P.Id, 
    ProjectName            = P.Name, 
    [UserType0 (Name)]     = MAX(CASE WHEN MemberType = 0 THEN u.Name END),
    [UserType0 (Register)] = MAX(CASE WHEN MemberType = 0 THEN Register END), 
    [UserType1 (Name)]     = MAX(CASE WHEN MemberType = 1 THEN u.Name END)

FROM 
(SELECT Proj.* 
 FROM Project AS Proj 
 LEFT JOIN ProjectMember AS Member ON Proj.Id = Member.Project_Id 
                                   AND Member.MemberType = 2
WHERE Member.User_Id = COALESCE(@UserId,Member.User_Id)  
 --changed this to use coalesce                      
) AS P
LEFT JOIN ProjectMember AS PM ON P.Id = PM.Project_Id
LEFT JOIN [User] AS U ON PM.User_Id = U.Id 
GROUP BY P.Id, P.Name;

希望这有帮助！

How to add a filter to find all project with a specific user

1 个答案: