如何將此 SQL 語句轉換為用於 C# 的 Linq

Question

我正在嘗試將我的簡單 SQL 語句轉換為我的 C# 應用程序的 Linq 格式，但我似乎總是在努力進行轉換。 我下載了 linqpad 並一直在玩它，但我仍然遇到正確格式的問題。

我的 SQL 語句：

SELECT distinct PictureCity, PictureState
FROM Website_Gallery
GROUP BY PictureCity, PictureState, PictureDate
ORDER BY PictureCity, PictureState

結果按 PictureCity 排序，如下所示：

Abington    MA
Acton   MA
Acushnet    MA
Agawam  MA
Andover MA
Arlington   MA
Arlington   TX
Ashby   MA
Ashland MA

到目前為止，我在 C# 應用程序中的內容似乎無法開始工作。 （我很討厭 linq）。

var Results = _context.Website_Gallery
.(g => g.PictureCity, g => g.PictureState).AsEnumerable()
.Select g
.GroupBy(g => g)

Answer 1

似乎你只需要

var results = _context.Website_Gallery
    .OrderBy(x => x.PictureCity)
    .ThenBy(x => x.PictureState)
    .Select(x => new { x.PictureCity, x.PictureState })
    .Distinct();

這將等同於以下 SQL

SELECT distinct PictureCity, PictureState
FROM Website_Gallery
ORDER BY PictureCity, PictureState

因為你所擁有的不需要組

請注意，然后您可以在foreach迭代該結果，也可以將ToList到末尾以將查詢具體化到內存中。

Answer 2

SQL

SELECT distinct PictureCity, PictureState
FROM Website_Gallery
ORDER BY PictureCity, PictureState

林克

var Results = _context.Website_Gallery
                  .Select(g => new { g.PictureCity, g.PictureState })
                  .Orderby(p => p.PictureCity).ThenBy(p => p.PictureState)
                  .Distinct().ToList();

或者你也可以這樣做

var Results = _context.Website_Gallery
            .GroupBy(x => new { PictureCity = x.PictureCity, PictureState = x.PictureState })
            .Select(g => new { g.Key.PictureCity, g.Key.PictureState }).Orderby(p => p.PictureCity).ThenBy(p => p.PictureState)
            .ToList();