Add unit test

Src/Asp.Net/SqlServerTest/SqlServerTest.csproj

@@ -97,6 +97,7 @@
     <Compile Include="UnitTest\UCustom01.cs" />
     <Compile Include="UnitTest\UCustom02.cs" />
     <Compile Include="UnitTest\UCustom03.cs" />
+    <Compile Include="UnitTest\UCustom04.cs" />
     <Compile Include="UnitTest\UDelete.cs" />
     <Compile Include="UnitTest\UFastest.cs" />
     <Compile Include="UnitTest\UConfig.cs" />

Src/Asp.Net/SqlServerTest/UnitTest/Main.cs

@@ -34,6 +34,7 @@ namespace OrmTest
             UCustom01.Init();
             UCustom02.Init();
             UCustom03.Init();
+            UCustom04.Init();
             SubQueryTest();
             UConfig();
             DeleteTest();

Src/Asp.Net/SqlServerTest/UnitTest/UCustom04.cs

@@ -0,0 +1,38 @@
+using SqlSugar;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace OrmTest 
+{
+    public class UCustom04
+    {
+        public static void Init() 
+        {
+            var db = NewUnitTest.Db;
+            var sql = db.Queryable<Order, OrderItem, Custom>((o, i, c) => new JoinQueryInfos(
+               JoinType.Left, o.Id == i.OrderId,
+               JoinType.Left, o.CustomId == c.Id
+           ))
+           .Select<ViewModel>().ToSql().Key;
+            UValidate.Check(sql, @"SELECT o.[Name] AS [Name],o.[Price] AS [Price],i.[OrderId] AS [OrderItemOrderId],i.[Price] AS [OrderItemPrice],c.[Name] AS [CustomName] FROM [Order] o Left JOIN [OrderDetail] i ON ( [o].[Id] = [i].[OrderId] )  Left JOIN [Custom] c ON ( [o].[CustomId] = [c].[Id] )","unit");
+            var list =
+                db.Queryable<Order, OrderItem, Custom>((o, i, c) => new JoinQueryInfos(
+               JoinType.Left, o.Id == i.OrderId,
+               JoinType.Left, o.CustomId == c.Id
+           ))
+           .Where((o,i,c)=>i.ItemId>0&&c.Id>0)
+           .Select<ViewModel>().ToList();
+        }
+        public class ViewModel
+        {
+            public string Name { get; set; }
+            public decimal Price { get; set; }
+            public int OrderItemOrderId { get; set; }
+            public int OrderItemPrice { get; set; }
+            public string CustomName { get; set; }
+        }
+    }
+}