SQL合并表

Question

我正在尝试合并几个表以获得输出，如下图所示。

我的问题是我不确定使用什么类型的连接来实现

有人可以帮我解释语法。

Answer 1

你可以做这样的事情，它可以作为动态支点，因为你可能会添加/带走用户？

CREATE TABLE #Tests (
    Test_ID INT,
    TestName VARCHAR(50));
INSERT INTO #Tests VALUES (1, 'SQL Test');
INSERT INTO #Tests VALUES (2, 'C# Test');
INSERT INTO #Tests VALUES (3, 'Java Test');
CREATE TABLE #Users (
    [User_ID] INT,
    UserName VARCHAR(50));
INSERT INTO #Users VALUES (1, 'Joe');
INSERT INTO #Users VALUES (2, 'Jack');
INSERT INTO #Users VALUES (3, 'Jane');
CREATE TABLE #UserTests (
    ID INT,
    [User_ID] INT,
    Test_ID INT,
    Completed INT);
INSERT INTO #UserTests VALUES (1, 1, 1, 0);
INSERT INTO #UserTests VALUES (2, 1, 2, 1);
INSERT INTO #UserTests VALUES (3, 1, 3, 1);
INSERT INTO #UserTests VALUES (4, 2, 1, 0);
INSERT INTO #UserTests VALUES (5, 2, 2, 0);
INSERT INTO #UserTests VALUES (6, 2, 3, 0);
INSERT INTO #UserTests VALUES (7, 3, 1, 1);
INSERT INTO #UserTests VALUES (8, 3, 2, 1);
INSERT INTO #UserTests VALUES (9, 3, 3, 1);
DECLARE @Cols VARCHAR(MAX);
SELECT @Cols = STUFF((SELECT distinct ',' + QUOTENAME(u.UserName) 
            FROM #Users u
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'');
DECLARE @Query NVARCHAR(MAX);
SELECT @Query = 'SELECT TestName, ' + @Cols + ' FROM
(
    SELECT 
        t.TestName,
        u.UserName,
        ut.Completed
FROM
    #Tests t
    INNER JOIN #UserTests ut ON ut.Test_ID = t.Test_ID
    INNER JOIN #Users u ON u.[User_ID] = ut.[User_ID]) x
    PIVOT (
        MAX(Completed)
        FOR UserName IN (' + @Cols + ')
    ) AS pt';
EXEC(@Query);

结果是：

TestName    Jack    Jane    Joe
C# Test     0       1       1
Java Test   0       1       1
SQL Test    0       1       0

（与您的结果相同，但排序顺序不同。）