From fd2829f5d62d94a85dcc2b677e58b0a5922d95b2 Mon Sep 17 00:00:00 2001
From: admin <570810310@qq.com>
Date: Mon, 15 Mar 2021 10:56:03 +0800
Subject: [PATCH] =?UTF-8?q?=E8=B7=9F=E6=96=B0=E5=88=AB=E5=90=8D=E7=94=A8?=
 =?UTF-8?q?=E6=B3=95?=
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Content-Transfer-Encoding: 8bit

---
 .../support/alias/AliasLambdaQueryWrapper.java | 18 +++++++++++++-----
 .../yulichang/common/support/alias/README.md   | 16 ++++++++++++----
 2 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/src/main/java/com/github/yulichang/common/support/alias/AliasLambdaQueryWrapper.java b/src/main/java/com/github/yulichang/common/support/alias/AliasLambdaQueryWrapper.java
index 856a63e..f92afcf 100644
--- a/src/main/java/com/github/yulichang/common/support/alias/AliasLambdaQueryWrapper.java
+++ b/src/main/java/com/github/yulichang/common/support/alias/AliasLambdaQueryWrapper.java
@@ -7,6 +7,14 @@ import com.baomidou.mybatisplus.core.toolkit.support.SFunction;
 
 /**
  * 字段添加别名
+ * 使用方法:
+ * <p>
+ * select t.* from table t ${ew.customSqlSegmentAlias("t")}
+ * <p>
+ * 注意:
+ * 官方的自定义sql是ew.customSqlSegment,不带括号,是属性
+ * 带别名的是 ew.customSqlSegment("t") 带括号,是方法
+ * 括号中的别名必须带双引号
  *
  * @author yulichang
  */
@@ -16,11 +24,6 @@ public class AliasLambdaQueryWrapper<T> extends LambdaQueryWrapper<T> {
      */
     private String alias;
 
-    public AliasLambdaQueryWrapper<T> setAlias(String alias) {
-        this.alias = alias;
-        return this;
-    }
-
     /**
      * 重写字段序列化方法
      */
@@ -29,4 +32,9 @@ public class AliasLambdaQueryWrapper<T> extends LambdaQueryWrapper<T> {
         String as = super.columnToString(column, onlyColumn);
         return StringUtils.isBlank(alias) ? as : (alias + StringPool.DOT + as);
     }
+
+    public String customSqlSegment(String alias) {
+        this.alias = alias;
+        return super.getCustomSqlSegment();
+    }
 }
diff --git a/src/main/java/com/github/yulichang/common/support/alias/README.md b/src/main/java/com/github/yulichang/common/support/alias/README.md
index 2c26b1a..bd809e2 100644
--- a/src/main/java/com/github/yulichang/common/support/alias/README.md
+++ b/src/main/java/com/github/yulichang/common/support/alias/README.md
@@ -17,6 +17,8 @@ AliasLambdaQueryWrapper继承LambdaQueryWrapper
 
 #### AliasLambdaQueryWrapper
 
+[感谢mybatis-plus PR 中的一位老哥的想法,以及实现](https://gitee.com/baomidou/mybatis-plus/pulls/137)
+
 注解:
 
 ```java
@@ -24,7 +26,7 @@ AliasLambdaQueryWrapper继承LambdaQueryWrapper
 @Mapper
 public interface UserMapper extends BaseMapper<UserDO> {
 
-    @Select("select u.*,ua.tel from user u left join user_address ua on u.id = ua.user_id ${ew.customSqlSegment}")
+    @Select("select u.*,ua.tel from user u left join user_address ua on u.id = ua.user_id ${ew.customSqlSegment(\"u\")}")
     UserDTO userLeftJoin(@Param(Constants.WRAPPER) Wrapper<?> queryWrapper);
 }
 ```
@@ -39,10 +41,15 @@ public interface UserMapper extends BaseMapper<UserDO> {
     from 
         user u
         left join user_address ua on u.id = ua.user_id
-    ${ew.customSqlSegment}
+    ${ew.customSqlSegment("u")}
 </select>
 ```
 
+注意:  
+官方的自定义sql是ew.customSqlSegment,不带括号,是属性  
+带别名的是 ew.customSqlSegment("t"),带括号,是方法  
+括号中的别名必须带双引号  
+
 使用wrapper:
 
 ```java
@@ -53,7 +60,6 @@ class MpJoinTest {
     @Test
     void test() {
         UserDTO userDTO = userMapper.userLeftJoin(new AliasLambdaQueryWrapper<UserDO>()
-                .setAlias("u")                //指定别名,要与注解或xml中的别名保持一致
                 .eq(UserDO::getId, "1")
                 .like(UserDO::getSex, "3"));
     }
@@ -102,7 +108,9 @@ class MpJoinTest {
     }
 }
 ```
+
 对应sql:
+
 ```
 select 
     u.*,
@@ -118,11 +126,11 @@ WHERE (
 
 注意:如果你喜欢骚操作,请使用原生QueryWrapper  
 举例:
+
 * .eq("(select sex from user where id = u.id)", "男")
 * .eq("count(u.id)", 1)
 
 不建议在QueryWrapper中使用sql或函数  
 除非你不考虑后续的维护和sql调优
 
-
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