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@ -1,6 +1,7 @@
# mybatis-plus-join # mybatis-plus-join
* 对 [mybatis-plus](https://gitee.com/baomidou/mybatis-plus) 多表查询的扩展 * 对 [mybatis-plus](https://gitee.com/baomidou/mybatis-plus) 多表查询的扩展
* 支持 mybatis <collection>和<association>标签
* [演示工程](https://gitee.com/best_handsome/mybatis-plus-join-demo) * [演示工程](https://gitee.com/best_handsome/mybatis-plus-join-demo)
* 点个Star支持一下吧 :) * 点个Star支持一下吧 :)
@ -15,12 +16,12 @@ QQ群:1022221898
<dependency> <dependency>
<groupId>com.github.yulichang</groupId> <groupId>com.github.yulichang</groupId>
<artifactId>mybatis-plus-join</artifactId> <artifactId>mybatis-plus-join</artifactId>
<version>1.2.4</version> <version>1.3.0</version>
</dependency> </dependency>
``` ```
- Gradle - 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 或者clone代码到本地执行 mvn install, 再引入以上依赖
<br> <br>
@ -35,7 +36,7 @@ QQ群:1022221898
### Lambda形式用法（MPJLambdaWrapper） ### Lambda形式用法（MPJLambdaWrapper）
#### 简单的三表查询 #### 简单的连表查询
```java ```java
class test { class test {
@ -43,17 +44,22 @@ class test {
private UserMapper userMapper; private UserMapper userMapper;
void testJoin() { void testJoin() {
List<UserDTO> list = userMapper.selectJoinList(UserDTO.class, MPJLambdaWrapper wrapper = new MPJLambdaWrapper<UserDO>()
new MPJLambdaWrapper<UserDO>() .selectAll(UserDO.class)//查询user表全部字段
.selectAll(UserDO.class) .select(UserAddressDO::getTel)//查询user_address tel 字段
.select(UserAddressDO::getTel) .selectAs(UserAddressDO::getAddress, UserDTO::getUserAddress)//别名 t.address AS userAddress
.selectAs(UserAddressDO::getAddress, UserDTO::getUserAddress) .select(AreaDO::getProvince, AreaDO::getCity)
.select(AreaDO::getProvince, AreaDO::getCity) .leftJoin(UserAddressDO.class, UserAddressDO::getUserId, UserDO::getId)
.leftJoin(UserAddressDO.class, UserAddressDO::getUserId, UserDO::getId) .leftJoin(AreaDO.class, AreaDO::getId, UserAddressDO::getAreaId)
.leftJoin(AreaDO.class, AreaDO::getId, UserAddressDO::getAreaId) .eq(UserDO::getId, 1)
.eq(UserDO::getId, 1) .like(UserAddressDO::getTel, "1")
.like(UserAddressDO::getTel, "1") .gt(UserDO::getId, 5);
.gt(UserDO::getId, 5));
//连表查询
List<UserDTO> list = userMapper.selectJoinList(UserDTO.class, wrapper);
//分页查询 （需要启用 mybatis plus 分页插件）
List<UserDTO> listPage = userMapper.selectJoinPage(new Page<>(2, 10), UserDTO.class, wrapper);
} }
} }
``` ```
@ -62,14 +68,9 @@ class test {
``` ```
SELECT SELECT
t.id, t.id, t.name, t.sex, t.head_img,
t.name, t1.tel, t1.address AS userAddress,
t.sex, t2.province, t2.city
t.head_img,
t1.tel,
t1.address AS userAddress,
t2.province,
t2.city
FROM FROM
user t user t
LEFT JOIN user_address t1 ON t1.user_id = t.id LEFT JOIN user_address t1 ON t1.user_id = t.id
@ -85,7 +86,6 @@ WHERE (
* UserDTO.class 查询结果返回类(resultType) * UserDTO.class 查询结果返回类(resultType)
* selectAll() 查询指定实体类的全部字段 * 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 * 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()
* 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 * 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 * leftJoin() 参数说明
第一个参数: 参与连表的实体类class 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.... * 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 * 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 #### 一对多查询
* [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
```java ```java
class test { class test {
@Resource @Resource
private UserMapper userMapper; private UserMapper userMapper;
void testJoin() { @Test
IPage<UserDTO> iPage = userMapper.selectJoinPage(new Page<>(2, 10), UserDTO.class, void testResultMap() {
new MPJLambdaWrapper<UserDO>() MPJLambdaWrapper<UserDO> wrapper = new MPJLambdaWrapper<UserDO>()
.selectAll(UserDO.class) .selectAll(UserDO.class)
.select(UserAddressDO::getTel) //一对多查询
.selectAs(UserAddressDO::getAddress, UserDTO::getUserAddress) .selectCollection(AddressDO.class, UDTO::getAddressList)
.select(AreaDO::getProvince, AreaDO::getCity) .leftJoin(AddressDO.class, AddressDO::getUserId, UserDO::getId);
.leftJoin(UserAddressDO.class, UserAddressDO::getUserId, UserDO::getId)
.leftJoin(AreaDO.class, AreaDO::getId, UserAddressDO::getAreaId)); List<UserDTO> dtoList = userMapper.selectJoinList(UserDTO.class, wrapper);
} }
} }
``` ```
对应sql 等效于ResultMap
```xml
<resultMap id="xxxxxxxx" type="com.github.yulichang.join.dto.UserDTO">
<result property="id" column="id"/>
<result property="name" column="name"/>
<collection property="addressList" javaType="java.util.List"
ofType="com.github.yulichang.join.entity.UserAddressDO">
<id property="id" column="mpj_id"/>
<result property="address" column="address"/>
<result property="userId" column="user_id"/>
</collection>
</resultMap>
``` ```
SELECT
t.id, MPJLambdaWrapper其他功能
t.name,
t.sex, * [一对一，一对多使用](https://gitee.com/best_handsome/mybatis-plus-join/wikis/MyLambdaWrapper/selectCollection()?sort_id=6509590)
t.head_img, * [简单的SQL函数使用](https://gitee.com/best_handsome/mybatis-plus-join/wikis/selectFunc()?sort_id=4082479)
t1.tel, * [ON语句多条件支持](https://gitee.com/best_handsome/mybatis-plus-join/wikis/leftJoin?sort_id=3496671)
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 ?,?
```
### String形式用法（MPJQueryWrapper） ### String形式用法（MPJQueryWrapper）
#### 简单的3表查询 #### 简单的连表查询
```java ```java
class test { class test {
@ -148,14 +146,19 @@ class test {
private UserMapper userMapper; private UserMapper userMapper;
void testJoin() { void testJoin() {
List<UserDTO> list = userMapper.selectJoinList(UserDTO.class, MPJQueryWrapper wrapper = new MPJQueryWrapper<UserDO>()
new MPJQueryWrapper<UserDO>() .selectAll(UserDO.class)
.selectAll(UserDO.class) .select("addr.tel", "addr.address", "a.province")
.select("addr.tel", "addr.address", "a.province") .leftJoin("user_address addr on t.id = addr.user_id")
.leftJoin("user_address addr on t.id = addr.user_id") .rightJoin("area a on addr.area_id = a.id")
.rightJoin("area a on addr.area_id = a.id") .like("addr.tel", "1")
.like("addr.tel", "1") .le("a.province", "1");
.le("a.province", "1"));
//列表查询
List<UserDTO> list = userMapper.selectJoinList(UserDTO.class, wrapper);
//分页查询 （需要启用 mybatis plus 分页插件）
List<UserDTO> 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) * 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 * 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<UserDTO> page = userMapper.selectJoinPage(new Page<>(1, 10), UserDTO.class,
new MPJQueryWrapper<UserDO>()
.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 #### 还可以这么操作,但不建议
```java ```java