Added sample to class reserved select queries

By creating a class with a pre-written selection query and defining rows, you can build queries using IntelliSense.

src/Carbunql.Postgres/SelectQuery.cs

@@ -1,12 +1,12 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-
-namespace Carbunql.Postgres;
+namespace Carbunql.Postgres;
 
 public class SelectQuery<T> : SelectQuery
 {
+    public SelectQuery() : base()
+    {
+    }
 
+    public SelectQuery(string query) : base(query)
+    {
+    }
 }

test/Carbunql.Postgres.Test/Carbunql.Postgres.Test.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
 

test/Carbunql.Postgres.Test/SampleQuery.cs

@@ -0,0 +1,31 @@
+namespace Carbunql.Postgres.Test;
+
+public static class SampleQuery
+{
+    public static string CommandText =>
+"""
+SELECT
+    a.a_id,
+    a.text,
+    b.value
+FROM
+    table_a AS a
+    INNER JOIN table_b AS b ON a.a_id = b.a_id
+""";
+
+    public static SelectQuery<Row> Query => GetQuery();
+
+    private static SelectQuery<Row>? QueryCache;
+
+    private static SelectQuery<Row> GetQuery()
+    {
+        if (QueryCache == null) QueryCache = new SelectQuery<Row>(CommandText);
+        return QueryCache;
+    }
+
+    public readonly record struct Row(
+        int a_id,
+        string text,
+        int value
+    );
+}

test/Carbunql.Postgres.Test/SubQueryText.cs

@@ -153,14 +153,43 @@ INNER JOIN RecordB AS b ON (a.a_id = b.a_id AND b.text = 'test')
         return sq;
     }
 
+
+    [Fact]
+    public void QueryClassTest()
+    {
+        var sq = new SelectQuery();
+        var (from, a) = sq.FromAs(SampleQuery.Query, "a");
+
+        sq.Select(() => a.a_id);
+        sq.Select(() => a.value * 2).As("value");
+
+        Monitor.Log(sq);
+
+        Assert.Equal(45, sq.GetTokens().ToList().Count);
+
+        var sql = @"SELECT
+    a.a_id,
+    a.value * 2 AS value
+FROM
+    (
+        SELECT
+            a.a_id,
+            a.text,
+            b.value
+        FROM
+            table_a AS a
+            INNER JOIN table_b AS b ON a.a_id = b.a_id
+    ) AS a";
+
+        Assert.Equal(sql, sq.ToText(), true, true, true);
+    }
+
     public record struct RecordA(int a_id, string text, int value, bool is_enabled, double rate, DateTime timestamp, Gender gender);
 
     public record struct RecordB(int a_id, int b_id, string text, int value);
 
     public record struct SubQueryRow(int a_id, string text, int value);
 
-    public class Myclass { public int MyProperty { get; set; } }
-
     public enum Gender
     {
         Male,