如何获取查询中列出现的索引？

Question

我正在尝试获取数据集中出现的列的索引/行号，以生成类似于以下内容的结果：

| Make        | Model    | Option    | Model Index |
├-------------+----------+-----------+-------------┤
| Lamborghini | Diablo   | SE30 Jota | 1           |
| Lamborghini | Diablo   | SE30      | 1           |
| Lamborghini | Cala     |           | 2           |
| Pontiac     | Trans AM | GTA       | 1           |
| Pontiac     | Trans AM | Firefox   | 1           |
| Pontiac     | GTO      | Judge     | 2           |
| Pontiac     | Fiero    | GT        | 3           |

请注意，对于具有不同选项的相同品牌和型号的汽车，型号索引应重复，但在制造更改时也应重置。我已设法找到 SQL 以在进行更改时进行重置，但是一旦包含选项列，我就会得到错误的结果。

SELECT
    Makes.Name,
    Models.Name,
    Options.Name,
    ROW_NUMBER() OVER (PARTITION BY Makes.Id ORDER BY Models.Name) [Model Index]
FROM 
    Makes
INNER JOIN  
    Models ON Models.MakeId = Makes.Id
INNER JOIN 
    Options ON Options.ModelId = Models.Id

此 SQL 的结果（不需要）：

| Make        | Model    | Option    | Model Index |
├-------------+----------+-----------+-------------┤
| Lamborghini | Diablo   | SE30 Jota | 1           |
| Lamborghini | Diablo   | SE30      | 2           |
| Lamborghini | Cala     |           | 3           |
| Pontiac     | Trans AM | GTA       | 1           |
| Pontiac     | Trans AM | Firefox   | 2           |
| Pontiac     | GTO      | Judge     | 3           |
| Pontiac     | Fiero    | GT        | 4           |

也许我这里的错误是我在查询中使用了 ROW_NUMBER 并且我认为行号不能在给定分区内重复。我想我需要 SomethingElse(PerhapsSomeReferenceToModel) OVER (PARTITION BY Makes.Id ORDER BY Models.Name) 但不知道 SomethingElse(PerhapsSomeReferenceToModel) 实际上应该是什么！

Answer 1

让我重新表述一下您的要求：

模型索引在进行更改时重置
相同型号的型号索引重复

如果模型索引不能包含间隙，则需要 RANK() 而不是 ROW_NUMBER() 或 DENSE_RANK()：

SELECT
    *,
    RANK() OVER (PARTITION BY Make ORDER BY Model) AS [Model Index],
    DENSE_RANK() OVER (PARTITION BY Make ORDER BY Model) AS [Model Index DENSE]
FROM @t
ORDER BY Make, Model

DB Fiddle

（上面的示例按 names 进行分区和排序。实际上，您实际上会做类似 PARTITION BY MakeID ORDER BY ModelID 的事情）。

Answer 2

对于 1-2-1-2-3 的结果，您的查询应该是正确的。 Table 别名也简化了查询：

SELECT ma.Name, mo.Name, o.Name,
       ROW_NUMBER() OVER (PARTITION BY mo.MakeId ORDER BY o.Name) as [Model Index]
FROM Makes ma INNER JOIN
     Models mo
     ON mo.MakeId = ma.Id INNER JOIN
     Options o
     ON o.ModelId = mo.Id;

我怀疑你想要 1-2-1-2-1。如果是这样，您需要更改 PARTITION BY:

SELECT ma.Name, mo.Name, o.Name,
       ROW_NUMBER() OVER (PARTITION BY mo.MakeId, mo.ModelId ORDER BY o.Name) as [Model Index]
FROM Makes ma INNER JOIN
     Models mo
     ON mo.MakeId = ma.Id INNER JOIN
     Options o
     ON o.ModelId = mo.Id

如何获取查询中列出现的索引？

How to get the index of a column's occurrence in a query?

sql

tsql

sql-server

row-number