Mybatis-Plus系列--进阶实例

其他网址

一文MyBatis-Plus快速入门 - 享智同行 - 博客园
mybatis-plus的使用 ------ 进阶 - 简书

本项目所有源码：https://gitee.com/shapeless/demo_MybtisPlus/tree/master/Complex

自定义SQL

其他网址

mybatis-plus之自定义sql、分页、Wrapper_CDN-CSDN博客_mybatisplus wrapper分页
Mybatisplus 自定义sql 使用条件构造器 - 静水165 - 博客园

自定义的sql使用Wrapper对版本有要求：mybatis-plus版本需要大于或等于3.0.7。

简介

值	含义
ew.customSqlSegment	条件构造器（Wrapper）
ew.sqlSet	所设置的列
ew.sqlSelect	要select的列

 

包里边定义好的常量。我们可以直接用这些常量。

mybatis-plus-core-3.3.2.jar\com\baomidou\mybatisplus\core\toolkit\Constants.class

package com.baomidou.mybatisplus.core.toolkit;

public interface Constants extends StringPool {
    String MYBATIS_PLUS = "mybatis-plus";
    String MD5 = "MD5";
    String AES = "AES";
    String AES_CBC_CIPHER = "AES/CBC/PKCS5Padding";
    String ENTITY = "et";
    String ENTITY_DOT = "et.";
    String WRAPPER = "ew";
    String WRAPPER_DOT = "ew.";
    String WRAPPER_ENTITY = "ew.entity";
    String WRAPPER_SQLSEGMENT = "ew.sqlSegment";
    String WRAPPER_EMPTYOFNORMAL = "ew.emptyOfNormal";
    String WRAPPER_NONEMPTYOFNORMAL = "ew.nonEmptyOfNormal";
    String WRAPPER_NONEMPTYOFENTITY = "ew.nonEmptyOfEntity";
    String WRAPPER_EMPTYOFWHERE = "ew.emptyOfWhere";
    String WRAPPER_NONEMPTYOFWHERE = "ew.nonEmptyOfWhere";
    String WRAPPER_ENTITY_DOT = "ew.entity.";
    String U_WRAPPER_SQL_SET = "ew.sqlSet";
    String Q_WRAPPER_SQL_SELECT = "ew.sqlSelect";
    String Q_WRAPPER_SQL_COMMENT = "ew.sqlComment";
    String Q_WRAPPER_SQL_FIRST = "ew.sqlFirst";
    String COLUMN_MAP = "cm";
    String COLUMN_MAP_IS_EMPTY = "cm.isEmpty";
    String COLLECTION = "coll";
    String WHERE = "WHERE";
    String MP_OPTLOCK_INTERCEPTOR = "oli";
    String MP_OPTLOCK_VERSION_ORIGINAL = "MP_OPTLOCK_VERSION_ORIGINAL";
    String MP_OPTLOCK_VERSION_COLUMN = "MP_OPTLOCK_VERSION_COLUMN";
    String MP_OPTLOCK_ET_ORIGINAL = "MP_OPTLOCK_ET_ORIGINAL";
    String WRAPPER_PARAM = "MPGENVAL";
    String WRAPPER_PARAM_FORMAT = "#{%s.paramNameValuePairs.%s}";
}

实例

entity

package com.example.entity;

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;

@Data
@TableName(value = "tb_user")//指定表名
public class User{
    //value与数据库主键列名一致，若实体类属性名与表主键列名一致可省略value
    @TableId(value = "id",type = IdType.ASSIGN_UUID)//指定自增策略
    private String id;
    private String name;

    //若没有开启驼峰命名，或者表中列名不符合驼峰规则，可通过该注解指定数据库表中的列名，exist标明数据表中有没有对应列
    @TableField(value = "last_name",exist = true)
    private String lastName;
    private String email;
    private Integer gender;
    private Integer age;
}

mapper

package com.example.mapper;

import com.baomidou.mybatisplus.core.conditions.Wrapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.example.entity.User;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;
import org.springframework.stereotype.Repository;

import java.util.List;
import java.util.Map;

@Repository
public interface UserMapper extends BaseMapper {
    @Select("select * from tb_user ${ew.customSqlSegment}")
    List testSelect1(@Param("ew") Wrapper wrapper);
//    List testSelect1(@Param(Constants.WRAPPER) Wrapper wrapper);

    @Select("select * from ${table_name} ${ew.customSqlSegment}")
    List testSelect2(@Param("table_name")String tableName, @Param("ew") Wrapper wrapper);

    @Select("select ${ew.SqlSelect} from ${table_name} ${ew.customSqlSegment}")
    List testSelect3(@Param("table_name")String tableName, @Param("ew") Wrapper wrapper);

    @Select("select ${ew.SqlSelect} from ${table_name} ${ew.customSqlSegment}")
    List> testSelect4(@Param("table_name")String tableName, @Param("ew") Wrapper wrapper);

    @Select("select * from ${table_name} where age = #{age}")
    List testSelect5(@Param("table_name")String tableName,  @Param("age")Integer age);

    @Select("select ${ew.SqlSelect} from ${table_name} where age = #{age} ${ew.customSqlSegment}")
    List testSelect6(@Param("table_name")String tableName,  @Param("age")Integer age,@Param("ew") Wrapper wrapper);

    @Select("select * from ${table_name} ${ew.customSqlSegment}")
    User testSelect7(@Param("table_name")String tableName,  @Param("ew") Wrapper wrapper);

    //只取name这一列
    @Select("SELECT tb_user.name FROM tb_user ${ew.customSqlSegment}")
    List getNames(@Param("ew") Wrapper