linq group min max

DevTips/.vscode/launch.json

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+{
+    // IntelliSense를 사용하여 가능한 특성에 대해 알아보세요.
+    // 기존 특성에 대한 설명을 보려면 가리킵니다.
+    // 자세한 내용을 보려면 https://go.microsoft.com/fwlink/?linkid=830387을(를) 방문하세요.
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "name": ".NET Core Launch (console)",
+            "type": "coreclr",
+            "request": "launch",
+            "preLaunchTask": "build",
+            "program": "${workspaceFolder}/DevTips/bin/Debug/net7.0/DevTips.dll",
+            "args": [],
+            "cwd": "${workspaceFolder}/DevTips",
+            "console": "internalConsole",
+            "stopAtEntry": false
+        },
+        {
+            "name": ".NET Core Attach",
+            "type": "coreclr",
+            "request": "attach"
+        }
+    ]
+}

DevTips/.vscode/tasks.json

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+{
+    "version": "2.0.0",
+    "tasks": [
+        {
+            "label": "build",
+            "command": "dotnet",
+            "type": "process",
+            "args": [
+                "build",
+                "${workspaceFolder}/DevTips/DevTips.csproj",
+                "/property:GenerateFullPaths=true",
+                "/consoleloggerparameters:NoSummary"
+            ],
+            "problemMatcher": "$msCompile"
+        },
+        {
+            "label": "publish",
+            "command": "dotnet",
+            "type": "process",
+            "args": [
+                "publish",
+                "${workspaceFolder}/DevTips/DevTips.csproj",
+                "/property:GenerateFullPaths=true",
+                "/consoleloggerparameters:NoSummary"
+            ],
+            "problemMatcher": "$msCompile"
+        },
+        {
+            "label": "watch",
+            "command": "dotnet",
+            "type": "process",
+            "args": [
+                "watch",
+                "run",
+                "--project",
+                "${workspaceFolder}/DevTips/DevTips.csproj"
+            ],
+            "problemMatcher": "$msCompile"
+        }
+    ]
+}

DevTips/DevTips.sln

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+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.0.31903.59
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "DevTips", "DevTips\DevTips.csproj", "{E0D7D3A3-0C0F-4499-BD11-13336302EB8D}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{E0D7D3A3-0C0F-4499-BD11-13336302EB8D}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{E0D7D3A3-0C0F-4499-BD11-13336302EB8D}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{E0D7D3A3-0C0F-4499-BD11-13336302EB8D}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{E0D7D3A3-0C0F-4499-BD11-13336302EB8D}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+EndGlobal

DevTips/DevTips/DevTips.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net7.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

DevTips/DevTips/Program.cs

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+using DevTips.Tips;
+
+namespace DevTips;
+class Program
+{
+    static void Main(string[] args)
+    {
+        LinqGroupMinMax.Print();
+        System.Console.WriteLine();
+        LinqGroupMinMax.Client1();
+        System.Console.WriteLine();
+        LinqGroupMinMax.Client2();
+    }
+}

DevTips/DevTips/Tips/LinqGroupMinMax.cs

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+using System.Data;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace DevTips.Tips
+{
+    class LinqGroupMinMax
+    {
+        public static void Print()
+        {
+            DataTable table = GetData();
+            foreach (DataRow row in table.Rows)
+            {
+                System.Console.WriteLine($"\t{row["GroupID"]}\t{row["SalesPerson"]}\t{row["Sales"]}");
+            }
+        }
+
+        public static void Client1()
+        {
+            var data = GetData().AsEnumerable();
+
+            var result = from row in data
+                         group row by row.Field<int>("GroupID") into g
+                         select new
+                         {
+                             GroupID = g.Key,
+                             SalesPerson = g.First(g2 => g2.Field<int>("Sales") == g.Min(g3 => g3.Field<int>("Sales"))).Field<string>("SalesPerson"),
+                             Sales = g.Min(p => p.Field<int>("Sales"))
+                         };
+
+            foreach (var r in result)
+            {
+                System.Console.WriteLine($"{r.GroupID},{r.SalesPerson} , {r.Sales}");
+            }
+        }
+
+        public static void Client2()
+        {
+            var data = GetData().AsEnumerable();
+
+            var result = data.GroupBy(t => t.Field<int>("GroupID")).Select(g => new
+            {
+                GroupID = g.Key,
+                SalesPerson = g.First(g2 => g2.Field<int>("Sales") == g.Min(g3 => g3.Field<int>("Sales"))).Field<string>("SalesPerson"),
+                Sales = g.Min(p => p.Field<int>("Sales"))
+            });
+        }
+
+        private static DataTable GetData()
+        {
+            DataTable table = new DataTable();
+            table.Columns.Add("GroupID", typeof(int));
+            table.Columns.Add("SalesPerson", typeof(string));
+            table.Columns.Add("Sales", typeof(int));
+
+            DataRow row = table.NewRow();
+            row["GroupID"] = 1;
+            row["SalesPerson"] = "Lee";
+            row["Sales"] = 900;
+            table.Rows.Add(row);
+
+            row = table.NewRow();
+            row["GroupID"] = 1;
+            row["SalesPerson"] = "Li";
+            row["Sales"] = 800;
+            table.Rows.Add(row);
+
+            row = table.NewRow();
+            row["GroupID"] = 1;
+            row["SalesPerson"] = "Park";
+            row["Sales"] = 990;
+            table.Rows.Add(row);
+
+            row = table.NewRow();
+            row["GroupID"] = 2;
+            row["SalesPerson"] = "Tom";
+            row["Sales"] = 500;
+            table.Rows.Add(row);
+
+            row = table.NewRow();
+            row["GroupID"] = 2;
+            row["SalesPerson"] = "Jane";
+            row["Sales"] = 400;
+            table.Rows.Add(row);
+
+            row = table.NewRow();
+            row["GroupID"] = 3;
+            row["SalesPerson"] = "Irina";
+            row["Sales"] = 600;
+            table.Rows.Add(row);
+
+            row = table.NewRow();
+            row["GroupID"] = 3;
+            row["SalesPerson"] = "Yong";
+            row["Sales"] = 633;
+            table.Rows.Add(row);
+
+            return table;
+        }
+    }
+}