From 477e5b921da672bb981ada299cfb2bb7ff2f2ce2 Mon Sep 17 00:00:00 2001 From: yulichang <570810310@qq.com> Date: Mon, 7 Nov 2022 18:06:38 +0800 Subject: [PATCH] =?UTF-8?q?1.2.5=E7=89=88=E6=9C=AC=E4=B8=B4=E6=97=B6?= =?UTF-8?q?=E5=88=86=E6=94=AF?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- README.md | 171 ++++++++++++++++++++++-------------------------------- 1 file changed, 68 insertions(+), 103 deletions(-) diff --git a/README.md b/README.md index 822e4ad..8bb8d96 100644 --- a/README.md +++ b/README.md @@ -1,6 +1,7 @@ # mybatis-plus-join * 对 [mybatis-plus](https://gitee.com/baomidou/mybatis-plus) 多表查询的扩展 +* 支持 mybatis 和标签 * [演示工程](https://gitee.com/best_handsome/mybatis-plus-join-demo) * 点个Star支持一下吧 :) @@ -15,12 +16,12 @@ QQ群:1022221898 com.github.yulichang mybatis-plus-join - 1.2.4 + 1.3.0 ``` - Gradle ``` - implementation 'com.github.yulichang:mybatis-plus-join:1.2.4' + implementation 'com.github.yulichang:mybatis-plus-join:1.3.0' ``` 或者clone代码到本地执行 mvn install, 再引入以上依赖
@@ -35,7 +36,7 @@ QQ群:1022221898 ### Lambda形式用法（MPJLambdaWrapper） -#### 简单的三表查询 +#### 简单的连表查询 ```java class test { @@ -43,17 +44,22 @@ class test { private UserMapper userMapper; void testJoin() { - List list = userMapper.selectJoinList(UserDTO.class, - new MPJLambdaWrapper() - .selectAll(UserDO.class) - .select(UserAddressDO::getTel) - .selectAs(UserAddressDO::getAddress, UserDTO::getUserAddress) - .select(AreaDO::getProvince, AreaDO::getCity) - .leftJoin(UserAddressDO.class, UserAddressDO::getUserId, UserDO::getId) - .leftJoin(AreaDO.class, AreaDO::getId, UserAddressDO::getAreaId) - .eq(UserDO::getId, 1) - .like(UserAddressDO::getTel, "1") - .gt(UserDO::getId, 5)); + MPJLambdaWrapper wrapper = new MPJLambdaWrapper() + .selectAll(UserDO.class)//查询user表全部字段 + .select(UserAddressDO::getTel)//查询user_address tel 字段 + .selectAs(UserAddressDO::getAddress, UserDTO::getUserAddress)//别名 t.address AS userAddress + .select(AreaDO::getProvince, AreaDO::getCity) + .leftJoin(UserAddressDO.class, UserAddressDO::getUserId, UserDO::getId) + .leftJoin(AreaDO.class, AreaDO::getId, UserAddressDO::getAreaId) + .eq(UserDO::getId, 1) + .like(UserAddressDO::getTel, "1") + .gt(UserDO::getId, 5); + + //连表查询 + List list = userMapper.selectJoinList(UserDTO.class, wrapper); + + //分页查询 （需要启用 mybatis plus 分页插件） + List listPage = userMapper.selectJoinPage(new Page<>(2, 10), UserDTO.class, wrapper); } } ``` @@ -61,15 +67,10 @@ class test { 对应sql ``` -SELECT - t.id, - t.name, - t.sex, - t.head_img, - t1.tel, - t1.address AS userAddress, - t2.province, - t2.city +SELECT + t.id, t.name, t.sex, t.head_img, + t1.tel, t1.address AS userAddress, + t2.province, t2.city FROM user t LEFT JOIN user_address t1 ON t1.user_id = t.id @@ -84,8 +85,7 @@ WHERE ( * UserDTO.class 查询结果返回类(resultType) * selectAll() 查询指定实体类的全部字段 -* select() 查询指定的字段,支持可变参数,同一个select只能查询相同表的字段 - 故将UserAddressDO和AreaDO分开为两个select() +* select() 查询指定的字段,支持可变参数,同一个select只能查询相同表的字段 * selectAs() 字段别名查询,用于数据库字段与业务实体类属性名不一致时使用 * leftJoin() 参数说明 第一个参数: 参与连表的实体类class @@ -94,53 +94,51 @@ WHERE ( * 默认主表别名是t,其他的表别名以先后调用的顺序使用t1,t2,t3.... * 条件查询,可以查询主表以及参与连接的所有表的字段,全部调用mp原生的方法,正常使用没有sql注入风险 -MPJLambdaWrapper其他功能 - -* [简单的SQL函数使用](https://gitee.com/best_handsome/mybatis-plus-join/wikis/selectFunc()?sort_id=4082479) -* [ON语句多条件支持](https://gitee.com/best_handsome/mybatis-plus-join/wikis/leftJoin?sort_id=3496671) - -#### 分页查询 +#### 一对多查询 ```java class test { @Resource private UserMapper userMapper; - void testJoin() { - IPage iPage = userMapper.selectJoinPage(new Page<>(2, 10), UserDTO.class, - new MPJLambdaWrapper() - .selectAll(UserDO.class) - .select(UserAddressDO::getTel) - .selectAs(UserAddressDO::getAddress, UserDTO::getUserAddress) - .select(AreaDO::getProvince, AreaDO::getCity) - .leftJoin(UserAddressDO.class, UserAddressDO::getUserId, UserDO::getId) - .leftJoin(AreaDO.class, AreaDO::getId, UserAddressDO::getAreaId)); + @Test + void testResultMap() { + MPJLambdaWrapper wrapper = new MPJLambdaWrapper() + .selectAll(UserDO.class) + //一对多查询 + .selectCollection(AddressDO.class, UDTO::getAddressList) + .leftJoin(AddressDO.class, AddressDO::getUserId, UserDO::getId); + + List dtoList = userMapper.selectJoinList(UserDTO.class, wrapper); } } ``` -对应sql +等效于ResultMap +```xml + + + + + + + + + + ``` -SELECT - t.id, - t.name, - t.sex, - t.head_img, - t1.tel, - t1.address AS userAddress, - t2.province, - t2.city -FROM - user t - LEFT JOIN user_address t1 ON t1.user_id = t.id - LEFT JOIN area t2 ON t2.id = t1.area_id -LIMIT ?,? -``` + +MPJLambdaWrapper其他功能 + +* [一对一，一对多使用](https://gitee.com/best_handsome/mybatis-plus-join/wikis/MyLambdaWrapper/selectCollection()?sort_id=6509590) +* [简单的SQL函数使用](https://gitee.com/best_handsome/mybatis-plus-join/wikis/selectFunc()?sort_id=4082479) +* [ON语句多条件支持](https://gitee.com/best_handsome/mybatis-plus-join/wikis/leftJoin?sort_id=3496671) ### String形式用法（MPJQueryWrapper） -#### 简单的3表查询 +#### 简单的连表查询 ```java class test { @@ -148,14 +146,19 @@ class test { private UserMapper userMapper; void testJoin() { - List list = userMapper.selectJoinList(UserDTO.class, - new MPJQueryWrapper() - .selectAll(UserDO.class) - .select("addr.tel", "addr.address", "a.province") - .leftJoin("user_address addr on t.id = addr.user_id") - .rightJoin("area a on addr.area_id = a.id") - .like("addr.tel", "1") - .le("a.province", "1")); + MPJQueryWrapper wrapper = new MPJQueryWrapper() + .selectAll(UserDO.class) + .select("addr.tel", "addr.address", "a.province") + .leftJoin("user_address addr on t.id = addr.user_id") + .rightJoin("area a on addr.area_id = a.id") + .like("addr.tel", "1") + .le("a.province", "1"); + + //列表查询 + List list = userMapper.selectJoinList(UserDTO.class, wrapper); + + //分页查询 （需要启用 mybatis plus 分页插件） + List listPage = userMapper.selectJoinPage(new Page<>(1, 10), UserDTO.class, wrapper); } } ``` @@ -189,44 +192,6 @@ WHERE ( * leftJoin() rightJoin() innerJoin() 传sql片段 格式 (表 + 别名 + 关联条件) * 条件查询,可以查询主表以及参与连接的所有表的字段,全部调用mp原生的方法,正常使用没有sql注入风险 -#### 分页查询 - -```java - -class test { - @Resource - private UserMapper userMapper; - - void testJoin() { - IPage page = userMapper.selectJoinPage(new Page<>(1, 10), UserDTO.class, - new MPJQueryWrapper() - .selectAll(UserDO.class) - .select("addr.tel", "addr.address") - .select("a.province") - .leftJoin("user_address addr on t.id = addr.user_id") - .rightJoin("area a on addr.area_id = a.id")); - } -} -``` - -对应sql - -``` -SELECT - t.id, - t.name, - t.sex, - t.head_img, - addr.tel, - addr.address, - a.province -FROM - user t - LEFT JOIN user_address addr on t.id = addr.user_id - RIGHT JOIN area a on addr.area_id = a.id -LIMIT ?,? -``` - #### 还可以这么操作,但不建议 ```java