Updated 多表查询 (markdown)

多表查询.md

@@ -76,29 +76,27 @@ fsql.Select<Topic, Category, CategoryType>()
 
 > 经验：[一对多，分表只取最后一条记录](https://github.com/dotnetcore/FreeSql/issues/430)
 
-## 3、WithSql
+## 3、WithoutJoin
+
+`WithoutJoin()` 方法提供了一种强大的机制，用于在 FreeSql 的多表查询（例如 `fsql.Select<T1, T2, T3>()`）中，**严格地控制哪些泛型类型对应的表最终会被 JOIN 到生成的 SQL 语句中**。这使得你可以在应用程序层面精确地动态构建查询，替代传统手动拼接 SQL 中对 JOIN 子句的条件控制。
 
 ```csharp
-fsql.Select<Topic, Category, CategoryType>()
+fsql.Select<Order, Product, User>()
-  .WithSql(
+    .InnerJoin((o, p, u) => o.UserId == u.Id)
-      "select * from Topic where id=@id1",
+    .LeftJoin((o, p, u) => o.ProductId == p.Id)
-      "select * from Category where id=@id2",
+    .WithoutJoin(t2: !includeProductInfo)
-      null, //不设置 CategoryType 对应的 SQL
+    .ToList((o, p, u) => new OrderDetailDto
-      new { id1 = 10, id2 = 11, id3 = 13 }
+    {
-  )
+        OrderId = o.Id,
-  .LeftJoin((a,b,c) => a.CategoryId == b.Id)
+        OrderNo = o.OrderNo,
-  .LeftJoin((a,b,c) => b.ParentId == c.Id)
+        Username = u.Username, // User (T3) 始终 JOIN，可直接引用
-  .ToList();
+        ProductName = includeProductInfo ? p.Name : "N/A"
-//SELECT ...
+    });
-//FROM ( select * from Topic where id=@id1 ) a
+
-//LEFT JOIN ( select * from Category where id=@id2 ) b ON a.`CategoryId` = b.`Id`
+// includeProductInfo = true: SQL 将 JOIN Product
-//LEFT JOIN `CategoryType` c ON b.`ParentId` = c.`Id`
+// includeProductInfo = false: SQL 将不 JOIN Product，ProductName 会是 "N/A"
 ```
 
-> 提示：ISelect.ToSql 可与 WithSql 配合使用
-
-> v3.2.666 [WithTempQuery + FromQuery 嵌套查询](%e5%b5%8c%e5%a5%97%e6%9f%a5%e8%af%a2)
-
 ## 4、SQL联表
 ```csharp
 fsql.Select<Topic>()