third_codes/mybatis-plus-join
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@ -10,6 +10,8 @@
## 使用方法
### 方法一
1. 将代码down到本地，使用maven install
2. 在自己的项目中替换mybatisplus依赖(框架依赖mybatisplus<3.4.2>)
@ -21,9 +23,16 @@
<version>1.0-SNAPSHOT</version>
</dependency>
```
### 方法二
1. 将mybatisplus目录复制到你的工程中
2. 如果mybatisplus目录不在springboot扫描路径下,
将MybatisPlusConfiguration移动到springboot扫描路径下或添加springboot扫描路径
### 使用
* entity继承MyBaseEntity (需要连表的实体类必须继承,其他可以不继承)
* mapper继承MyBaseMapper (必选)
* service继承MyBaseService (可选)
* serviceImpl继承MyBaseServiceImpl (可选)
@ -38,12 +47,14 @@
class test {
@Resource
private UserMapper userMapper;
void testJoin() {
List<UserDTO> list = userMapper.selectJoinList(new MyLambdaQueryWrapper<UserEntity>()
.select(UserEntity::getHeadImg, UserEntity::getName)
.leftJoin(UserEntity::getId, UserAddressEntity::getUserId,
right -> right.select(UserAddressEntity::getAddress, UserAddressEntity::getTel))
.selectAll(UserEntity.class)
.leftJoin(UserEntity::getId, UserAddressEntity::getUserId, r1 -> r1
.select(UserAddressEntity::getAddress)
.leftJoin(UserAddressEntity::getAreaId, AreaEntity::getId,
r2 -> r2.select(AreaEntity::getProvince)))
, UserDTO.class);
}
}
@ -52,14 +63,15 @@ class test {
对应sql
```sql
SELECT
t0.head_img,
t0.name,
t1.address,
t1.tel
FROM
user t0
LEFT JOIN user_address t1 ON t0.id = t1.user_id
SELECT t0.name,
t0.sex,
t0.head_img,
t0.id,
t1.address,
t2.province
FROM user t0
LEFT JOIN user_address t1 ON t0.id = t1.user_id
LEFT JOIN area t2 ON t1.area_id = t2.id
```
#### selectAll(UserEntity.class) 查询UserEntity全部字段
@ -84,16 +96,14 @@ class test {
对应sql
```sql
SELECT
t0.name,
t0.sex,
t0.head_img,
t0.id,
t1.address,
t1.tel
FROM
user t0
LEFT JOIN user_address t1 ON t0.id = t1.user_id
SELECT t0.name,
t0.sex,
t0.head_img,
t0.id,
t1.address,
t1.tel
FROM user t0
LEFT JOIN user_address t1 ON t0.id = t1.user_id
```
#### as(UserEntity::getHeadImg,UserDTO::getUserHeadImg)
@ -118,13 +128,11 @@ class test {
对应sql
```sql
SELECT
t0.head_img AS userHeadImg,
t1.address,
t1.tel
FROM
user t0
LEFT JOIN user_address t1 ON t0.id = t1.user_id
SELECT t0.head_img AS userHeadImg,
t1.address,
t1.tel
FROM user t0
LEFT JOIN user_address t1 ON t0.id = t1.user_id
```
#### 左连接 leftJoin(UserEntity::getId,UserAddressEntity::getUserId,right -> right)
@ -156,20 +164,18 @@ class test {
对应sql
```sql
SELECT
t0.name,
t0.sex,
t0.head_img,
t0.id,
t1.address,
t1.tel
FROM
user t0
LEFT JOIN user_address t1 ON t0.id = t1.user_id
SELECT t0.name,
t0.sex,
t0.head_img,
t0.id,
t1.address,
t1.tel
FROM user t0
LEFT JOIN user_address t1 ON t0.id = t1.user_id
WHERE (
t0.id = ?
AND t1.tel LIKE ?
AND t0.id = t1.user_id)
t0.id = ?
AND t1.tel LIKE ?
AND t0.id = t1.user_id)
```
#### [参考测试类](https://gitee.com/best_handsome/mybatis-plus-join/blob/master/src/test/java/com/example/mp/MpJoinTest.java)