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README.md
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[goto wiki](https://gitee.com/best_handsome/mybatis-plus-join/wikis)
## 通用连表wrapper
[点击跳转至使用方法](https://gitee.com/best_handsome/mybatis-plus-join/tree/master/src/main/java/com/github/yulichang/common)
### 安装
1. 在项目中添加依赖,依赖已经包含了mybatis-plus-boot-starter<3.4.2><br>
@ -80,6 +84,108 @@ MPJLambdaQueryWrapper相当于mp的LambdaQueryWrapper
MPJQueryWrapper.lambda() ===> MPJLambdaQueryWrapper
MPJLambdaQueryWrapper.stringQuery() ===> MPJQueryWrapper
## MPJJoinLambdaQueryWrapper用法
#### MPJJoinLambdaQueryWrapper示例
#### 简单的3表查询
```java
class test {
@Resource
private UserMapper userMapper;
void testJoin() {
List<UserDTO> list = userMapper.selectJoinList(UserDTO.class,
new MPJJoinLambdaQueryWrapper<UserDO>()
.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(true, UserDO::getId, 1)
.like(true, UserAddressDO::getTel, "1")
.gt(true, UserDO::getId, 5));
}
}
```
对应sql
```
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
WHERE (
t.id = ?
AND t1.tel LIKE ?
AND t.id > ?)
```
说明:
* 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()
* 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
第二个参数: 连表的ON字段,这个属性必须是第一个参数实体类的属性
第三个参数: 参与连表的ON的另一个实体类属性
* 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
#### 分页查询
```java
class test {
@Resource
private UserMapper userMapper;
void testJoin() {
IPage<UserDTO> iPage = userMapper.selectJoinPage(new Page<>(2, 10), UserDTO.class,
new MPJJoinLambdaQueryWrapper<UserDO>()
.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));
}
}
```
对应sql
```
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 ?,?
```
## MPJQueryWrapper和MPJLambdaQueryWrapper
### 简单的3表查询
@ -227,112 +333,6 @@ ORDER BY
addr.id DESC
```
## MPJJoinLambdaQueryWrapper用法
MPJJoinLambdaQueryWrapper与上面连个Wrapper不同,是一套新的支持多表的wrapper
MPJQueryWrapper是基于QueryWrapper扩展的MPJLambdaQueryWrapper是基于LambdaQueryWrapper扩展的
而LambdaQueryWrapper由于泛型约束,不支持扩展成多表的lambdaWrapper
#### MPJJoinLambdaQueryWrapper示例
#### 简单的3表查询
```java
class test {
@Resource
private UserMapper userMapper;
void testJoin() {
List<UserDTO> list = userMapper.selectJoinList(UserDTO.class,
new MPJJoinLambdaQueryWrapper<UserDO>()
.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(true, UserDO::getId, 1)
.like(true, UserAddressDO::getTel, "1")
.gt(true, UserDO::getId, 5));
}
}
```
对应sql
```
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
WHERE (
t.id = ?
AND t1.tel LIKE ?
AND t.id > ?)
```
说明:
* 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()
* 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
第二个参数: 连表的ON字段,这个属性必须是第一个参数实体类的属性
第三个参数: 参与连表的ON的另一个实体类属性
* 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
#### 分页查询
```java
class test {
@Resource
private UserMapper userMapper;
void testJoin() {
IPage<UserDTO> iPage = userMapper.selectJoinPage(new Page<>(2, 10), UserDTO.class,
new MPJJoinLambdaQueryWrapper<UserDO>()
.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));
}
}
```
对应sql
```
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 ?,?
```
# [wiki](https://gitee.com/best_handsome/mybatis-plus-join/wikis)

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@ -2,6 +2,14 @@
### 使用方法
#### 如需单独使用 请拷贝以下5个类
[com.github.yulichang.common.JoinLambdaWrapper](https://gitee.com/best_handsome/mybatis-plus-join/blob/master/src/main/java/com/github/yulichang/common/JoinLambdaWrapper.java)
[com.github.yulichang.common.JoinAbstractWrapper](https://gitee.com/best_handsome/mybatis-plus-join/blob/master/src/main/java/com/github/yulichang/common/JoinAbstractLambdaWrapper.java)
[com.github.yulichang.common.JoinAbstractLambdaWrapper](https://gitee.com/best_handsome/mybatis-plus-join/blob/master/src/main/java/com/github/yulichang/common/JoinAbstractLambdaWrapper.java)
[com.github.yulichang.wrapper.interfaces.Compare](https://gitee.com/best_handsome/mybatis-plus-join/blob/master/src/main/java/com/github/yulichang/wrapper/interfaces/Compare.java)
[com.github.yulichang.wrapper.interfaces.Func](https://gitee.com/best_handsome/mybatis-plus-join/blob/master/src/main/java/com/github/yulichang/wrapper/interfaces/Func.java)
#### 不使用表别名
注解: