From 07a2bb72a1f3bf899e87ba19446cabc390643eba Mon Sep 17 00:00:00 2001
From: 2881099 <2881099@qq.com>
Date: Fri, 10 Mar 2023 20:34:26 +0800
Subject: [PATCH] update

---
 API.md         |  1 +
 Update-Data.md | 51 +++++++++++++++++++++++++++++++++++++++++++++++++-
 修改.md        | 51 +++++++++++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 101 insertions(+), 2 deletions(-)

diff --git a/API.md b/API.md
index 162bcb1..bf68dfd 100644
--- a/API.md
+++ b/API.md
@@ -233,6 +233,7 @@ DbContext 自身 = 完整事务，BaseRepository 不一定有事务（可通过
 | ToSql | string | | 返回即将执行的SQL语句 |
 | ExecuteAffrows | long | | 执行SQL语句，返回影响的行数 |
 | ExecuteUpdated | List\<T1\> | | 执行SQL语句，返回更新后的记录 |
+| Join | IUpdateJoin | | 联表更新 |
 
 ---
 
diff --git a/Update-Data.md b/Update-Data.md
index f81d6a9..75563a4 100644
--- a/Update-Data.md
+++ b/Update-Data.md
@@ -250,7 +250,55 @@ The benefits of using this program for dang complex update:
 - Data can be previewed before updating to prevent wrong update operations;
 - Support complex update operations, for example: Use `Limit(10)` on `ISelect` to update the first 10 records that meet the conditions;
 
-## 11、BulkCopy Batch Update
+## 11、UpdateJoin
+
+v3.2.692+ (High risk operation, high risk operation, high risk operation, please use with caution, test and check the content returned by ToSql)
+
+```csharp
+fsql.Update<T1>()
+  .Join<T2>((a, b) => a.id == b.groupid)
+  .Set((a, b) => a.bname == b.name)
+  .Set((a, b) => a.bcode == b.id + a.code)
+  .Set(a => a.flag, 1) //Fixed value
+  .Where((a, b) => a.id > 0 && b.id > 0)
+  .ExecuteAffrows();
+```
+
+The SQL generated by different databases is different. Take MySql as an example:
+
+```sql
+UPDATE `T1` a
+INNER JOIN `T2` b ON (a.`id` = b.`groupid`)
+SET a.`bname` = b.`name`, a.`bcode` = concat(b.`id`, a.`code`), a.`flag` = 1
+WHERE a.`id` > 0 AND b.`id` > 0
+```
+
+More complex joint table update:
+
+```csharp
+var query = fsql.Select<T2, T3>()
+  .InnerJoin(...)
+  .Where(...)
+  .WithTempQuery((a, b) => new { item1 = a, item2 = b });
+
+fsql.Update<T1>()
+  .Join(query, (a, b) => a.id == b.item1.groupid)
+  .Set((a, b) => a.bcode == b.item2.xcode)
+  .ExecuteAffrows();
+```
+
+```sql
+UPDATE `T1` a
+INNER JOIN (
+  SELECT ...
+  FROM `t2` a
+  INNER JOIN ...
+  Where ...
+) b ON (a.`id` = b.`groupid`)
+SET a.`bcode` = b.`xcode`
+```
+
+## 12、BulkCopy Batch Update
 
 FreeSql.Provider.SqlServer、FreeSql.Provider.MySqlConnector、FreeSql.Provider. PostgreSQL
 
@@ -293,3 +341,4 @@ fsql.Update<T1>().SetSource(list).ExecuteSqlBulkCopy();
 | ToSql | string | | Return the SQL statement to be executed |
 | ExecuteAffrows | long | | Execute SQL statement and return the number of rows affected |
 | ExecuteUpdated | List\<T1\> | | Execute SQL statement and return the updated record |
+| Join | IUpdateJoin | | 联表更新 |
diff --git a/修改.md b/修改.md
index 77edf9c..401c714 100644
--- a/修改.md
+++ b/修改.md
@@ -253,7 +253,55 @@ UPDATE `T1` SET Title = '111' WHERE id in (select a.id from T1 a left join Optio
 - 更新前可预览测试数据，防止错误更新操作；
 - 支持复杂的更新操作，例如：`ISelect` 上使用 `Limit(10)` 更新附合条件的前 10 条记录；
 
-## 11、BulkCopy 批量更新
+## 11、联表更新 UpdateJoin
+
+v3.2.692+（高风险操作，高风险操作，高风险操作，请谨慎谨慎谨慎使用，测试并核对 ToSql 返回的内容）
+
+```csharp
+fsql.Update<T1>()
+  .Join<T2>((a, b) => a.id == b.groupid)
+  .Set((a, b) => a.bname == b.name) //其他表字段
+  .Set((a, b) => a.bcode == b.id + a.code)
+  .Set(a => a.flag, 1) //固定值
+  .Where((a, b) => a.id > 0 && b.id > 0)
+  .ExecuteAffrows();
+```
+
+不同数据库产生的 SQL 不一样，以 MySql 为例：
+
+```sql
+UPDATE `T1` a
+INNER JOIN `T2` b ON (a.`id` = b.`groupid`)
+SET a.`bname` = b.`name`, a.`bcode` = concat(b.`id`, a.`code`), a.`flag` = 1
+WHERE a.`id` > 0 AND b.`id` > 0
+```
+
+更复杂的联表更新：
+
+```csharp
+var query = fsql.Select<T2, T3>()
+  .InnerJoin(...)
+  .Where(...)
+  .WithTempQuery((a, b) => new { item1 = a, item2 = b });
+
+fsql.Update<T1>()
+  .Join(query, (a, b) => a.id == b.item1.groupid)
+  .Set((a, b) => a.bcode == b.item2.xcode)
+  .ExecuteAffrows();
+```
+
+```sql
+UPDATE `T1` a
+INNER JOIN (
+  SELECT ...
+  FROM `t2` a
+  INNER JOIN ...
+  Where ...
+) b ON (a.`id` = b.`groupid`)
+SET a.`bcode` = b.`xcode`
+```
+
+## 12、BulkCopy 批量更新
 
 FreeSql.Provider.SqlServer、FreeSql.Provider.MySqlConnector、FreeSql.Provider.PostgreSQL 
 
@@ -296,3 +344,4 @@ fsql.Update<T1>().SetSource(list).ExecuteSqlBulkCopy();
 | ToSql | string | | 返回即将执行的 SQL 语句 |
 | ExecuteAffrows | long | | 执行 SQL 语句，返回影响的行数 |
 | ExecuteUpdated | List\<T1\> | | 执行 SQL 语句，返回更新后的记录 |
+| Join | IUpdateJoin | | 联表更新 |