1. 简介
官网 https://mybatisplusjoin.com/
2. 基本用法
步骤:
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添加依赖
XML<!--mybatis-plus-join--> <dependency> <groupId>com.github.yulichang</groupId> <artifactId>mybatis-plus-join-boot-starter</artifactId> <version>1.4.5</version> </dependency>
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编辑EmpMapper.java,继承自MPJBaseMapper
javapublic interface EmpMapper extends MPJBaseMapper<Emp> { }
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测试
java@SpringBootTest class EmpMapperTest { @Resource private EmpMapper empMapper; @Test public void selectAll(){ MPJLambdaWrapper<Emp> wrapper = new MPJLambdaWrapper<Emp>() .selectAll(Emp.class) // 查询Emp类的所有字段 .selectAs(Dept::getName, EmpDTO::getDeptName)// 查询Dept类的name字段 .leftJoin(Dept.class, Dept::getId, Emp::getDeptId) // 左连接 .orderByDesc(Emp::getId); List<EmpDTO> list = empMapper.selectJoinList(EmpDTO.class, wrapper); list.forEach(System.out::println); } @Test public void selectByPage(){ Page<EmpDTO> page = new Page<>(1, 3); empMapper.selectJoinPage(page, EmpDTO.class, new MPJLambdaWrapper<Emp>() .selectAll(Emp.class) .selectAs(Dept::getName, EmpDTO::getDeptName) .leftJoin(Dept.class, Dept::getId, Emp::getDeptId) .eq(Dept::getId, 1)); page.getRecords().forEach(System.out::println); } }