update

Query-from-Multi-Tables.md

@@ -182,7 +182,20 @@ fsql.Select<Category>().ToList(a => new  {
 });
 ```
 
-## 9. Collection properties
+## 9、Subtable: ToList
+
+> v3.2.650+
+
+```csharp
+fsql.Select<Topic>().ToList(a => new
+{
+  all = a,
+  list1 = fsql.Select<T2>().ToList(),
+  list2 = fsql.Select<T2>().Where(b => b.TopicId == a.Id).ToList()
+});
+```
+
+## 10. Collection properties
 
 ```csharp
 fsql.Select<Category>()
@@ -200,7 +213,7 @@ fsql.Select<Category>()
 
 Quickly convert the collection properties to `ISelect` for sub-query operations.
 
-## 10. WhereCascade
+## 11. WhereCascade
 
 When querying multiple tables, it is troublesome to add conditions to each table like `ISelect`, and `WhereCascade` came into being. After using `WhereCascade`, when SQL is generated, all tables will be attached to this condition.
 

多表查询.md

@@ -172,7 +172,20 @@ fsql.Select<Category>().ToList(a => new  {
 });
 ```
 
-## 9、集合属性
+## 9、子表ToList
+
+> v3.2.650+ 以下最多执行3次 SQL
+
+```csharp
+fsql.Select<Topic>().ToList(a => new
+{
+  all = a,
+  list1 = fsql.Select<T2>().ToList(),
+  list2 = fsql.Select<T2>().Where(b => b.TopicId == a.Id).ToList()
+});
+```
+
+## 10、集合属性
 
 ```csharp
 fsql.Select<Category>()
@@ -190,7 +203,7 @@ fsql.Select<Category>()
 
 将集合属性快速转换为 ISelect 进行子查询操作。
 
-## 10、WhereCascade
+## 11、WhereCascade
 
 多表查询时，像isdeleted每个表都给条件，挺麻烦的。WhereCascade使用后生成sql时，所有表都附上这个条件。
 

表达式函数.md

@@ -115,38 +115,84 @@ fsql.Select<T>()
 
 ```csharp
 fsql.Select<T1, T2>()
-.InnerJoin((a, b) => b.Id == a.Id)
-.ToList((a, b) => new
-{
-    Id = a.Id,
-    EdiId = b.Id,
-    over1 = SqlExt.Rank().Over().OrderBy(a.Id).OrderByDescending(b.EdiId).ToValue()
-});
+  .InnerJoin((a, b) => b.Id == a.Id)
+  .ToList((a, b) => new
+  {
+      Id = a.Id,
+      EdiId = b.Id,
+      over1 = SqlExt.Rank().Over().OrderBy(a.Id).OrderByDescending(b.EdiId).ToValue()
+  });
 ```
 
 > v1.6.0 利用自定义解析功能，增加 SqlExt.Rank().Over().PartitionBy(...)、MySql group_concat 常用函数，欢迎 PR 补充
 
-## 返回子查询字段
+## 子表Exists
+
+```c#
+fsql.Select<Topic>()
+  .Where(a => fsql.Select<Topic>().As("b").Where(b => b.Id == a.Id).Any())
+  .ToList();
+//SELECT a.`Id`, a.`Title`, a.`Clicks`, a.`CreateTime`, a.`CategoryId`
+//FROM `Topic` a
+//WHERE (exists(SELECT 1
+//    FROM `Topic` b
+//    WHERE (b.`Id` = a.`Id`)
+//    limit 0,1))
+```
+
+> 提示：由于子查询的实体类与上层相同，使用 As("b") 指明别名，以便区分
+
+## 子表In
+
+```c#
+fsql.Select<Topic>()
+  .Where(a => fsql.Select<Topic>().As("b").ToList(b => b.Id).Contains(a.Id))
+  .ToList();
+//SELECT a.`Id`, a.`Title`, a.`Clicks`, a.`CreateTime`, a.`CategoryId`
+//FROM `Topic` a
+//WHERE (((a.`Id`) in (SELECT b.`Id`
+//    FROM `Topic` b)))
+```
+
+## 子表Join
+> v1.8.0+ string.Join + ToList 实现将子查询的多行结果，拼接为一个字符串，如："1,2,3,4"
+
+```c#
+fsql.Select<Topic>().ToList(a => new {
+  id = a.Id,
+  concat = string.Join(",", fsql.Select<StringJoin01>().ToList(b => b.Id))
+});
+//SELECT a.`Id`, (SELECT group_concat(b.`Id` separator ',') 
+//    FROM `StringJoin01` b) 
+//FROM `Topic` a
+```
+
+> 提示：子查询 string.Join + ToList 适配了 sqlserver/pgsql/oracle/mysql/sqlite/firebird/达梦/金仓/南大/翰高 [#405](https://github.com/dotnetcore/FreeSql/issues/405)
+
+## 子表First/Count/Sum/Max/Min/Avg
 
 ```csharp
-List<匿名类> t10 = fsql.Select<Topic>().ToList(a => new {
-    a.Id,
-    count = fsql.Select<T2>().Count(),
-    max = fsql.Select<T2>().Max(b => b.Id),
-    min = fsql.Select<T2>().Min(b => b.Id),
-    name = fsql.Select<2>().First(b => b.name)
+fsql.Select<Category>().ToList(a => new  {
+  all = a,
+  first = fsql.Select<Topic>().Where(b => b.CategoryId == a.Id).First(b => b.Id),
+  count = fsql.Select<Topic>().Where(b => b.CategoryId == a.Id).Count(),
+  sum = fsql.Select<Topic>().Where(b => b.CategoryId == a.Id).Sum(b => b.Clicks),
+  max = fsql.Select<Topic>().Where(b => b.CategoryId == a.Id).Max(b => b.Clicks),
+  min = fsql.Select<Topic>().Where(b => b.CategoryId == a.Id).Min(b => b.Clicks),
+  avg = fsql.Select<Topic>().Where(b => b.CategoryId == a.Id).Avg(b => b.Clicks)
 });
 ```
 
-## 返回子查询集合
+## 子表ToList
 
 > v3.2.650+ 以下最多执行3次 SQL
 
 ```csharp
-List<匿名类> t11 = fsql.Select<Topic>().ToList(a => new {
-    a.Id,
-    list1 = fsql.Select<T2>().ToList(),
-    list2 = fsql.Select<T2>().Where(b => b.TopicId == a.Id).ToList()
+fsql.Select<Topic>().ToList(a => new
+{
+  all = a,
+  list1 = fsql.Select<T2>().ToList(),
+  list2 = fsql.Select<T2>().Where(b => b.TopicId == a.Id).ToList()
 });
 ```