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Question

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根据第一张图片，我在数据表中有数据，但想要转换我的数据表或使用第二张图片中的新输出创建一个新的数据表

                var reportData = (from C in Table1
                                  join LC in Table2 on C.Id equals LC.Id
                                  select new { C.Id, C.User, LC.Phy, LC.Che, LC.Bio, LC.Math }).ToList();

                foreach (var item in reportData)
                {

                    lstLc.Add(new Launch() { Username= item.User, Phy = item.Phy, Che = item.Che, Bio = item.Bio, Math = item.Math });
        }

原始数据：Output needed

User    Phy    Che    Bio    Math
A       12     20     16     10
B       15     19     18     20
C       13     17     11     18

需要输出..

User    Type    value
A       Phy     12
A       Che     20
A       Bio     16
A       Math    10
B       Phy     15
B       Che     19
B       Bio     18
B       Math    20
C       Phy     13
C       Che     17
C       Bio     11
C       Math    18

Answer 1

你可以像这样使用union：

SELECT User, Type, value FROM (
    SELECT User, 'Phy' AS 'Type', Phy AS 'value' FROM table1
    UNION
    SELECT User, 'Che' AS 'Type', Che AS 'value' FROM table1
    UNION
    SELECT User, 'Bio' AS 'Type', Bio AS 'value' FROM table1
    UNION
    SELECT User, 'Math' AS 'Type', Math AS 'value' FROM table1
) AS t
ORDER BY User

在 LINQ 中，您可以执行以下操作：

var list = entity.Select(e => new { User = e.User, Type = "Phy", value = e.Phy })
    .Union(entity.Select(e => new { User = e.User, Type = "Che", value = e.Che }))
    .Union(entity.Select(e => new { User = e.User, Type = "Bio", value = e.Bio }))
    .Union(entity.Select(e => new { User = e.User, Type = "Math", value = e.Math }))
    .OrderBy(e => e.User);

编辑将您的代码更改为：

var repFlatData = (from C in Table1
                   join LC in Table2 on C.Id equals LC.Id
                   select new { C.Id, C.User, LC.Phy, LC.Che, LC.Bio, LC.Math }).ToList();

var reportData = repFlatData.Select(e => new { User = e.User, Type = "Phy", value = e.Phy })
          .Union(repFlatData.Select(e => new { User = e.User, Type = "Che", value = e.Che }))
          .Union(repFlatData.Select(e => new { User = e.User, Type = "Bio", value = e.Bio }))
          .Union(repFlatData.Select(e => new { User = e.User, Type = "Math", value = e.Math }))
          .OrderBy(e => e.User);

foreach (var item in reportData) {
    lstLc.Add(new Launch() { Username= item.User, Type = item.Type, Value = item.Value });
}

当然，您需要将 Launch 类更改为仅包含列（用户名、类型、值）。