Sql server SELECT语句中的SQL WHERE语句

我正在进行一个查询，该查询从表的行中获取数据并将其放在同一列下：

SELECT [t].*,
       [d].[Description] AS [Name],
FROM   [TrainerClass] AS [t] join [DescriptionTranslation] AS [d] on [t].[Code] = [d].[Code]
WHERE  [d].[TableName] = 'TrainerClass' AND 
       [d].[FieldName] = 'Name' AND 
       [d].[Language] = 'en-EN';

这很好，但它只返回一列。我希望通过更多的列得到相同的结果，但我不知道如何使用WHERE语句。我想实现以下目标：

SELECT [t].*,
       [d].[Description] AS [Name] WHERE [d].[FieldName] = 'Name',
       [d].[Description] AS [Info] WHERE [d].[FieldName] = 'Info',
FROM   [TrainerClass] AS [t] join [DescriptionTranslation] AS [d] on [t].[Code] = [d].[Code]
WHERE  [d].[TableName] = 'TrainerClass' AND 
       [d].[Language] = 'en-EN';

我知道这不是一个正确的语法，这就是为什么我问你如何得到这个结果。提前感谢：）

编辑：

我不想要的是：

我想要的是：

---

（仅使用一条记录制作的示例，应该有更多）

如果我正确地阅读了您的请求，您需要使用不同的筛选器加入表两次

select t.*, dName.Description as [Name], dInfo.Description as [Info]
from TrainerClass t
join DescriptionTranslation dName
    on t.Code = dName.Code and dName.FieldName = 'Name'
join DescriptionTranslation dInfo
    on t.Code = dInfo.Code and dInfo.FieldName = 'Info'
where
    dName.TableName = 'TrainerClass' and dName.Language = 'en-EN'
    and dInfo.TableName = 'TrainerClass' and dInfo.Language = 'en-EN'

---

您可以使用下面这样的

CASE

语句（我想这就是您要找的）。请注意，在每种情况下，不匹配的行将得到空值，或者您可以将else部分添加到case语句中

SELECT [t].*,
       CASE WHEN [d].[FieldName] = 'Name' THEN [d].[Description] END AS [Name],
       CASE WHEN [d].[FieldName] = 'Info' THEN [d].[Description] END AS [Info]

FROM   [TrainerClass] AS [t] join [DescriptionTranslation] AS [d] 
                             on [t].[Code] = [d].[Code]
WHERE  [d].[TableName] = 'TrainerClass' AND  --[d].[FieldName] = 'Name' AND 
       [d].[Language] = 'en-EN';

更新：

根据您的更新，要从显示的图片表中获得预期结果，您可以将

Max（）

函数与

分组依据一起使用

：

;With cte as 
(
    --your first query goes here 
)
Select Id,Code, Max(Name) Name, Max(info) Info
from cte
Group by Id, Code

当然，您可以在不使用CTE的情况下执行以下操作：

SELECT t.Id, t.Code,
       Max(CASE WHEN d.FieldName = 'Name' THEN d.Description END) AS Name,
       Max(CASE WHEN d.FieldName = 'Info' THEN d.Description END) AS Info
FROM   [TrainerClass] AS t join [DescriptionTranslation] AS d  on t.Code = d.Code
WHERE  d.TableName = 'TrainerClass' AND  --[d].[FieldName] = 'Name' AND 
       d.Language = 'en-EN'
GROUP BY t.Id, t.Code;

---

另一种方法是使用子查询进行查询，这与您的意图非常相似。但是这种方法只有一个警告，那就是如果你有大的记录集，它会非常慢

---

---

使用下面的

交叉应用

进行查询

SELECT  [t].*,
        [DTNameDescription].[Description] AS [Name]
        [DTInfoDescription].[Description] AS [Info] 
FROM    [TrainerClass] AS [t] 
        CROSS APPLY (
            SELECT  [Description] 
            FROM    [DescriptionTranslation] AS [d] 
            WHERE   [t].[Code] = [d].[Code] 
                        AND [d].[FieldName] = 'Name'
        ) AS DTNameDescription
        CROSS APPLY (
            SELECT  [Description] 
            FROM    [DescriptionTranslation] AS [d] 
            WHERE   [t].[Code] = [d].[Code] 
                        AND [d].[FieldName] = 'Info'
        ) AS DTInfoDescription
WHERE   [d].[TableName] = 'TrainerClass' AND 
        [d].[Language] = 'en-EN';

---

我觉得它看起来不错，但不幸的是它没有返回任何数据。不过，没有语法错误…请尝试执行

左连接

，而不是只执行

连接

（默认情况下为内部连接）。看看这是否给了您任何提示，说明为什么没有得到匹配。我希望具有相同代码的列的值位于同一行上。有什么简单的方法吗？不知道你说的是什么意思。如果你提供一个提琴，并用预期的结果更新你的问题，它将很容易理解和解决。在这里，你可以查看我以前的答案：希望它有帮助。我也在用预期的结果更新问题。更新了，你能检查一下吗？这段代码是到目前为止我发现的最好的代码，但很糟糕，它不能正常工作。我已经更新了如何从你不想要的东西中得到你想要的东西。

SELECT  [t].*,
        [DTNameDescription].[Description] AS [Name]
        [DTInfoDescription].[Description] AS [Info] 
FROM    [TrainerClass] AS [t] 
        CROSS APPLY (
            SELECT  [Description] 
            FROM    [DescriptionTranslation] AS [d] 
            WHERE   [t].[Code] = [d].[Code] 
                        AND [d].[FieldName] = 'Name'
        ) AS DTNameDescription
        CROSS APPLY (
            SELECT  [Description] 
            FROM    [DescriptionTranslation] AS [d] 
            WHERE   [t].[Code] = [d].[Code] 
                        AND [d].[FieldName] = 'Info'
        ) AS DTInfoDescription
WHERE   [d].[TableName] = 'TrainerClass' AND 
        [d].[Language] = 'en-EN';