# mybatis-plus4
**Repository Path**: x92021/mybatis-plus4
## Basic Information
- **Project Name**: mybatis-plus4
- **Description**: mybatis-plus 4.0 临时仓库
- **Primary Language**: Unknown
- **License**: Apache-2.0
- **Default Branch**: master
- **Homepage**: http://baomidou.com/
- **GVP Project**: No
## Statistics
- **Stars**: 0
- **Forks**: 16
- **Created**: 2022-04-16
- **Last Updated**: 2024-05-31
## Categories & Tags
**Categories**: Uncategorized
**Tags**: None
## README
Born To Simplify Development
> 规划计划
[官方文档](http://baomidou.com)
[企业版 Mybatis-Mate 高级特性](https://gitee.com/baomidou/mybatis-mate-examples)
### 多表Join支持使用说明
1、准备2个po
```java
@Data
@TableName(value="user")
public class User {
@TableId("user_id")
private Integer userId;
@TableField("name")
private String name;
@TableField("age")
private Integer age;
@TableField("sex")
private String sex;
//指定这个字段和School 的id字段关联，如果不是和id字段关联可以使用targetFields属性进行关联
@TableField(value="school_id",target = School.class)
private Integer schoolId;
//指定关联关系，和目标类 如果是 onetoone 则不需要指定target
@TableField(relation = Relation.ONE_TO_MANY,target = School.class)
List schools;
}
```
```java
@Data
@TableName(value="school",autoResultMap = true) //这里设置自动生成resultMap 不需要别的操作
public class School {
@TableId
private Integer id;
@TableField("school_name")
private String schoolName;
@TableField("remark")
private String remark;
}
```
2、使用BasicJoinQueryWrapper (为po advance query预留的，不推荐开发者直接使用)
```java
BasicJoinQueryWrapper wrapper = new BasicJoinQueryWrapper<>(User.class);
wrapper.innerJoin(School.class);
wrapper.eq(new BasicJoinQueryWrapper.ModelProperty(User.class,"schoolId"),1);
wrapper.select(new BasicJoinQueryWrapper.ModelProperty(User.class,"schoolId"));
wrapper.select(new BasicJoinQueryWrapper.ModelProperty(User.class,"userId"));
wrapper.select(new BasicJoinQueryWrapper.ModelProperty(User.class,"name"));
wrapper.select(new BasicJoinQueryWrapper.ModelProperty(School.class,"schoolName"));
wrapper.select(new BasicJoinQueryWrapper.ModelProperty(School.class,"id"));
wrapper.select(new BasicJoinQueryWrapper.ModelProperty(School.class,"remark"));
mapper.selectJoinList(wrapper);
```
po advance query写法 ：
```java
new User().select(User.SCHOOLID,User.USERID,User.NAME).userId().eq(1).innerJoin(School.class).orgName().like("一").select(School.ID,School.REMARK,School.SCHOOLNAME).list();
```
需要mybatis-plus-advance 依赖：https://gitee.com/baomidou/mybatis-plus-advance
3、使用LambdaJoinQueryWrapper
```java
LambdaJoinQueryWrapper wrapper = new LambdaJoinQueryWrapper<>(User.class);
wrapper.eq(User::getSchoolId,1);
wrapper.innerJoin(School.class).like(School::getSchoolName,"一");
mapper.selectJoinList(wrapper);
```
### 函数支持
改动：在query接口中添加了selectFun方法，支持用户使用函数来查询字段，目前各类wrapper实现均已支持此查询
```java
Children selectFun(BaseFuncEnum fun,R alias,R column)
```
1、po上添加接收函数返回的字段
```java
@TableField(exist = false,funField = true) //标记数据库不存在，并且是个函数字段
private Long schoolCount;
```
2、各类wrapper使用
```java
// QueryWrapper
new QueryWrapper().eq("school_id",2).select("school_id").selectFun(DefaultFuncEnum.COUNT,
"schoolCount").groupBy("school_id")
// LambdaQueryWrapper
new LambdaQueryWrapper().eq(User::getSchoolId,2)
.select(User::getSchoolId).selectFun(DefaultFuncEnum.COUNT,User::getSchoolCount).groupBy(User::getSchoolId)
// QueryChainWrapper
QueryChainWrapper wrapper = new QueryChainWrapper(mapper);
wrapper.eq("school_id",2).select("school_id").selectFun(DefaultFuncEnum.COUNT,
"schoolCount").groupBy("school_id").one()
// LambdaQueryChainWrapper
LambdaQueryChainWrapper wrapper = new LambdaQueryChainWrapper(mapper);
wrapper.eq(User::getSchoolId,2) .select(User::getSchoolId).selectFun(DefaultFuncEnum.COUNT,User::getSchoolCount).groupBy(User::getSchoolId).one()
// BasicJoinQueryWrapper
BasicJoinQueryWrapper wrapper = new BasicJoinQueryWrapper<>(User.class);
wrapper.eq(new BasicJoinQueryWrapper.ModelProperty(User.class,"schoolId"),2);
wrapper.select(new BasicJoinQueryWrapper.ModelProperty(User.class,"schoolId"));
wrapper.selectFun(DefaultFuncEnum.COUNT,new BasicJoinQueryWrapper.ModelProperty(User.class,"schoolCount"));
wrapper.groupBy(new BasicJoinQueryWrapper.ModelProperty(User.class,"schoolId"));
// LambdaJoinQueryWrapper
LambdaJoinQueryWrapper wrapper = new LambdaJoinQueryWrapper<>(User.class);
wrapper.eq(User::getSchoolId,2);
wrapper.select(User::getSchoolId);
wrapper.selectFun(DefaultFuncEnum.COUNT,User::getSchoolCount);
wrapper.groupBy(User::getSchoolId);
```
### 批量插入支持说明
1.目前已经支持的数据库有：mysql,oracle,postgresql,sqlserver
2.序列自增配置：
```java
/**
* Postgre 主键生成器
* @return
*/
@Bean
public IKeyGenerator keyGenerator() {
return new PostgreKeyGenerator(); // oracle和Postgre 序列生成主键都已经支持
}
/**
* 序列自增插件
*/
@Bean
public MybatisPlusInterceptor mybatisPlusInterceptor() {
MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
//需要依赖此拦截器
interceptor.addInnerInterceptor(new KeyGeneratorInterceptor());
return interceptor;
}
```
3.数据库类型配置(也可以配置到@tablename注解里，注解优先于全局配置)
```yaml
mybatis-plus:
global-config:
db-config:
# 数据库类型
db-type: mysql
```
### 批量修改支持说明
1.目前已经支持的数据库有：mysql,oracle,postgresql
2.已知问题-oracle返回的受影响行数不对