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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843

answer CHANGED
@@ -1,71 +1,71 @@
1
- こんな感じでどうでしょうか。
2
-
3
- ```lang-c#
4
- using System;
5
- using System.Linq;
6
-
7
- namespace LinqSample {
8
- class Program {
9
- static void Main(string[] args) {
10
- var traders = new Trader[] {
11
- new Trader() { Id = 1, CompanyNm = "株式会社ABC", Address = "北海道" },
12
- new Trader() { Id = 2, CompanyNm = "株式会社DEF", Address = "青森" },
13
- new Trader() { Id = 3, CompanyNm = "株式会社GHI", Address = "秋田" },
14
- new Trader() { Id = 4, CompanyNm = "株式会社HIJ", Address = "岩手" },
15
- new Trader() { Id = 5, CompanyNm = "株式会社KLM", Address = "山形" },
16
- new Trader() { Id = 6, CompanyNm = "株式会社OPQ", Address = "宮城" },
17
- };
18
-
19
- var items = new ItemList[] {
20
- new ItemList() { Id = 1, Price = 100, ExpiryDate = new DateTime(2000, 4, 1) },
21
- new ItemList() { Id = 2, Price = 200, ExpiryDate = new DateTime(2005, 5, 1) },
22
- new ItemList() { Id = 3, Price = 300, ExpiryDate = new DateTime(2010, 6, 1) },
23
- new ItemList() { Id = 4, Price = 400, ExpiryDate = new DateTime(2015, 7, 1) },
24
- new ItemList() { Id = 5, Price = 2020, ExpiryDate = new DateTime(2020, 8, 1) }
25
- };
26
-
27
- var result = traders.GroupJoin(
28
- items,
29
- trader => trader.Id,
30
- item => item.Id,
31
- (trader, item) => new { trader, item })
32
- // シーケンスの展開
33
- .SelectMany(traderAndItem => traderAndItem.item, (trader, item) => new {
34
- Id = trader.trader.Id,
35
- CompanyNm = trader.trader.CompanyNm,
36
- Address = trader.trader.Address,
37
- Price = item.Price,
38
- ExpireDate = item.ExpiryDate
39
- })
40
- .Where(o => o.ExpireDate > new DateTime(2010, 1, 1))
41
- .ToList();
42
-
43
- foreach (var o in result) {
44
- Console.WriteLine($"Id={o.Id}, CompanyNm={o.CompanyNm}, Address={o.Address}, Price={o.Price}, ExpireDate={o.ExpireDate}");
45
- }
46
- }
47
- }
48
-
49
- class Trader {
50
- public int Id { get; set; }
51
- public string CompanyNm { get; set; }
52
- public string Address { get; set; }
53
- }
54
-
55
- class ItemList {
56
- public int Id { get; set; }
57
- public int Price { get; set; }
58
- public DateTime ExpiryDate { get; set; }
59
- }
60
- }
61
-
62
-
63
- ```
64
-
65
- 出力。
66
-
67
- ```
68
- Id=3, CompanyNm=株式会社GHI, Address=秋田, Price=300, ExpireDate=10/06/01 0:00:00
69
- Id=4, CompanyNm=株式会社HIJ, Address=岩手, Price=400, ExpireDate=15/07/01 0:00:00
70
- Id=5, CompanyNm=株式会社KLM, Address=山形, Price=2020, ExpireDate=20/08/01 0:00:00
1
+ こんな感じでどうでしょうか。
2
+
3
+ ```c#
4
+ using System;
5
+ using System.Linq;
6
+
7
+ namespace LinqSample {
8
+ class Program {
9
+ static void Main(string[] args) {
10
+ var traders = new Trader[] {
11
+ new Trader() { Id = 1, CompanyNm = "株式会社ABC", Address = "北海道" },
12
+ new Trader() { Id = 2, CompanyNm = "株式会社DEF", Address = "青森" },
13
+ new Trader() { Id = 3, CompanyNm = "株式会社GHI", Address = "秋田" },
14
+ new Trader() { Id = 4, CompanyNm = "株式会社HIJ", Address = "岩手" },
15
+ new Trader() { Id = 5, CompanyNm = "株式会社KLM", Address = "山形" },
16
+ new Trader() { Id = 6, CompanyNm = "株式会社OPQ", Address = "宮城" },
17
+ };
18
+
19
+ var items = new ItemList[] {
20
+ new ItemList() { Id = 1, Price = 100, ExpiryDate = new DateTime(2000, 4, 1) },
21
+ new ItemList() { Id = 2, Price = 200, ExpiryDate = new DateTime(2005, 5, 1) },
22
+ new ItemList() { Id = 3, Price = 300, ExpiryDate = new DateTime(2010, 6, 1) },
23
+ new ItemList() { Id = 4, Price = 400, ExpiryDate = new DateTime(2015, 7, 1) },
24
+ new ItemList() { Id = 5, Price = 2020, ExpiryDate = new DateTime(2020, 8, 1) }
25
+ };
26
+
27
+ var result = traders.GroupJoin(
28
+ items,
29
+ trader => trader.Id,
30
+ item => item.Id,
31
+ (trader, item) => new { trader, item })
32
+ // シーケンスの展開
33
+ .SelectMany(traderAndItem => traderAndItem.item, (trader, item) => new {
34
+ Id = trader.trader.Id,
35
+ CompanyNm = trader.trader.CompanyNm,
36
+ Address = trader.trader.Address,
37
+ Price = item.Price,
38
+ ExpireDate = item.ExpiryDate
39
+ })
40
+ .Where(o => o.ExpireDate > new DateTime(2010, 1, 1))
41
+ .ToList();
42
+
43
+ foreach (var o in result) {
44
+ Console.WriteLine($"Id={o.Id}, CompanyNm={o.CompanyNm}, Address={o.Address}, Price={o.Price}, ExpireDate={o.ExpireDate}");
45
+ }
46
+ }
47
+ }
48
+
49
+ class Trader {
50
+ public int Id { get; set; }
51
+ public string CompanyNm { get; set; }
52
+ public string Address { get; set; }
53
+ }
54
+
55
+ class ItemList {
56
+ public int Id { get; set; }
57
+ public int Price { get; set; }
58
+ public DateTime ExpiryDate { get; set; }
59
+ }
60
+ }
61
+
62
+
63
+ ```
64
+
65
+ 出力。
66
+
67
+ ```
68
+ Id=3, CompanyNm=株式会社GHI, Address=秋田, Price=300, ExpireDate=10/06/01 0:00:00
69
+ Id=4, CompanyNm=株式会社HIJ, Address=岩手, Price=400, ExpireDate=15/07/01 0:00:00
70
+ Id=5, CompanyNm=株式会社KLM, Address=山形, Price=2020, ExpireDate=20/08/01 0:00:00
71
71
  ```

2

refactor

2021/10/24 03:19

投稿

jhashimoto
jhashimoto

スコア843

answer CHANGED
@@ -7,7 +7,7 @@
7
7
  namespace LinqSample {
8
8
  class Program {
9
9
  static void Main(string[] args) {
10
- Trader[] traders = new Trader[] {
10
+ var traders = new Trader[] {
11
11
  new Trader() { Id = 1, CompanyNm = "株式会社ABC", Address = "北海道" },
12
12
  new Trader() { Id = 2, CompanyNm = "株式会社DEF", Address = "青森" },
13
13
  new Trader() { Id = 3, CompanyNm = "株式会社GHI", Address = "秋田" },
@@ -16,7 +16,7 @@
16
16
  new Trader() { Id = 6, CompanyNm = "株式会社OPQ", Address = "宮城" },
17
17
  };
18
18
 
19
- ItemList[] items = new ItemList[] {
19
+ var items = new ItemList[] {
20
20
  new ItemList() { Id = 1, Price = 100, ExpiryDate = new DateTime(2000, 4, 1) },
21
21
  new ItemList() { Id = 2, Price = 200, ExpiryDate = new DateTime(2005, 5, 1) },
22
22
  new ItemList() { Id = 3, Price = 300, ExpiryDate = new DateTime(2010, 6, 1) },
@@ -30,12 +30,12 @@
30
30
  item => item.Id,
31
31
  (trader, item) => new { trader, item })
32
32
  // シーケンスの展開
33
- .SelectMany(o => o.item, (o, p) => new {
33
+ .SelectMany(traderAndItem => traderAndItem.item, (trader, item) => new {
34
- Id = o.trader.Id,
34
+ Id = trader.trader.Id,
35
- CompanyNm = o.trader.CompanyNm,
35
+ CompanyNm = trader.trader.CompanyNm,
36
- Address = o.trader.Address,
36
+ Address = trader.trader.Address,
37
- Price = p.Price,
37
+ Price = item.Price,
38
- ExpireDate = p.ExpiryDate
38
+ ExpireDate = item.ExpiryDate
39
39
  })
40
40
  .Where(o => o.ExpireDate > new DateTime(2010, 1, 1))
41
41
  .ToList();
@@ -58,6 +58,8 @@
58
58
  public DateTime ExpiryDate { get; set; }
59
59
  }
60
60
  }
61
+
62
+
61
63
  ```
62
64
 
63
65
  出力。

1

ToListを追加

2021/10/24 03:19

投稿

jhashimoto
jhashimoto

スコア843

answer CHANGED
@@ -37,7 +37,8 @@
37
37
  Price = p.Price,
38
38
  ExpireDate = p.ExpiryDate
39
39
  })
40
- .Where(o => o.ExpireDate > new DateTime(2010, 1, 1));
40
+ .Where(o => o.ExpireDate > new DateTime(2010, 1, 1))
41
+ .ToList();
41
42
 
42
43
  foreach (var o in result) {
43
44
  Console.WriteLine($"Id={o.Id}, CompanyNm={o.CompanyNm}, Address={o.Address}, Price={o.Price}, ExpireDate={o.ExpireDate}");
@@ -57,7 +58,6 @@
57
58
  public DateTime ExpiryDate { get; set; }
58
59
  }
59
60
  }
60
-
61
61
  ```
62
62
 
63
63
  出力。