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トップLINQに関する質問C# LINQでJOINをした結果をWHERE句で抽出レコードを限定する方法

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3

言語指定の誤りを修正

2022/08/16 13:37

投稿

jhashimoto
jhashimoto

スコア838

test CHANGED
@@ -1,141 +1,71 @@
1
1
  こんな感じでどうでしょうか。
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2
 
3
-
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-
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- ```lang-c#
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+ ```c#
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-
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  using System;
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-
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  using System.Linq;
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6
 
11
-
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-
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  namespace LinqSample {
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-
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  class Program {
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-
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9
  static void Main(string[] args) {
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-
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  var traders = new Trader[] {
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-
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  new Trader() { Id = 1, CompanyNm = "株式会社ABC", Address = "北海道" },
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-
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  new Trader() { Id = 2, CompanyNm = "株式会社DEF", Address = "青森" },
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-
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  new Trader() { Id = 3, CompanyNm = "株式会社GHI", Address = "秋田" },
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-
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  new Trader() { Id = 4, CompanyNm = "株式会社HIJ", Address = "岩手" },
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-
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  new Trader() { Id = 5, CompanyNm = "株式会社KLM", Address = "山形" },
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-
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  new Trader() { Id = 6, CompanyNm = "株式会社OPQ", Address = "宮城" },
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-
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17
  };
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18
 
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-
36
-
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  var items = new ItemList[] {
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  new ItemList() { Id = 1, Price = 100, ExpiryDate = new DateTime(2000, 4, 1) },
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-
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  new ItemList() { Id = 2, Price = 200, ExpiryDate = new DateTime(2005, 5, 1) },
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-
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  new ItemList() { Id = 3, Price = 300, ExpiryDate = new DateTime(2010, 6, 1) },
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-
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  new ItemList() { Id = 4, Price = 400, ExpiryDate = new DateTime(2015, 7, 1) },
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-
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  new ItemList() { Id = 5, Price = 2020, ExpiryDate = new DateTime(2020, 8, 1) }
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  };
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-
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-
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  var result = traders.GroupJoin(
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-
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  items,
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-
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  trader => trader.Id,
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-
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  item => item.Id,
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  (trader, item) => new { trader, item })
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-
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  // シーケンスの展開
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-
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  .SelectMany(traderAndItem => traderAndItem.item, (trader, item) => new {
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-
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  Id = trader.trader.Id,
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-
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  CompanyNm = trader.trader.CompanyNm,
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-
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  Address = trader.trader.Address,
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-
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  Price = item.Price,
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-
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  ExpireDate = item.ExpiryDate
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-
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  })
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-
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  .Where(o => o.ExpireDate > new DateTime(2010, 1, 1))
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-
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  .ToList();
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42
 
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-
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-
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43
  foreach (var o in result) {
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-
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44
  Console.WriteLine($"Id={o.Id}, CompanyNm={o.CompanyNm}, Address={o.Address}, Price={o.Price}, ExpireDate={o.ExpireDate}");
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-
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45
  }
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-
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  }
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-
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47
  }
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95
-
96
-
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  class Trader {
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-
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  public int Id { get; set; }
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-
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  public string CompanyNm { get; set; }
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-
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  public string Address { get; set; }
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-
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  }
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54
 
107
-
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-
109
55
  class ItemList {
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-
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56
  public int Id { get; set; }
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-
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  public int Price { get; set; }
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-
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  public DateTime ExpiryDate { get; set; }
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-
117
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  }
118
-
119
60
  }
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-
121
-
122
-
123
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124
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125
63
  ```
126
64
 
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-
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-
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  出力。
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66
 
131
-
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-
133
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  ```
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-
135
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  Id=3, CompanyNm=株式会社GHI, Address=秋田, Price=300, ExpireDate=10/06/01 0:00:00
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-
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  Id=4, CompanyNm=株式会社HIJ, Address=岩手, Price=400, ExpireDate=15/07/01 0:00:00
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-
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  Id=5, CompanyNm=株式会社KLM, Address=山形, Price=2020, ExpireDate=20/08/01 0:00:00
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-
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  ```

2

refactor

2021/10/24 03:19

投稿

jhashimoto
jhashimoto

スコア838

test CHANGED
@@ -16,7 +16,7 @@
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16
 
17
17
  static void Main(string[] args) {
18
18
 
19
- Trader[] traders = new Trader[] {
19
+ var traders = new Trader[] {
20
20
 
21
21
  new Trader() { Id = 1, CompanyNm = "株式会社ABC", Address = "北海道" },
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22
 
@@ -34,7 +34,7 @@
34
34
 
35
35
 
36
36
 
37
- ItemList[] items = new ItemList[] {
37
+ var items = new ItemList[] {
38
38
 
39
39
  new ItemList() { Id = 1, Price = 100, ExpiryDate = new DateTime(2000, 4, 1) },
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40
 
@@ -62,17 +62,17 @@
62
62
 
63
63
  // シーケンスの展開
64
64
 
65
- .SelectMany(o => o.item, (o, p) => new {
65
+ .SelectMany(traderAndItem => traderAndItem.item, (trader, item) => new {
66
66
 
67
- Id = o.trader.Id,
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+ Id = trader.trader.Id,
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68
 
69
- CompanyNm = o.trader.CompanyNm,
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+ CompanyNm = trader.trader.CompanyNm,
70
70
 
71
- Address = o.trader.Address,
71
+ Address = trader.trader.Address,
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72
 
73
- Price = p.Price,
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+ Price = item.Price,
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74
 
75
- ExpireDate = p.ExpiryDate
75
+ ExpireDate = item.ExpiryDate
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76
 
77
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  })
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78
 
@@ -118,6 +118,10 @@
118
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119
119
  }
120
120
 
121
+
122
+
123
+
124
+
121
125
  ```
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126
 
123
127
 

1

ToListを追加

2021/10/24 03:19

投稿

jhashimoto
jhashimoto

スコア838

test CHANGED
@@ -76,7 +76,9 @@
76
76
 
77
77
  })
78
78
 
79
- .Where(o => o.ExpireDate > new DateTime(2010, 1, 1));
79
+ .Where(o => o.ExpireDate > new DateTime(2010, 1, 1))
80
+
81
+ .ToList();
80
82
 
81
83
 
82
84
 
@@ -116,8 +118,6 @@
116
118
 
117
119
  }
118
120
 
119
-
120
-
121
121
  ```
122
122
 
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