条件构造器

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QueryWrapper

1 组装查询条件

@Testpublicvoidtest01(){QueryWrapper<User>queryWrapper=newQueryWrapper<>();queryWrapper.like("name","a").between("age",20,30).isNotNull("email");List<User>list=userMapper.selectList(queryWrapper);list.forEach(System.out::println);}

2 组装排序条件

@Testpublicvoidtest02(){QueryWrapper<User>queryWrapper=newQueryWrapper<>();queryWrapper.orderByDesc("age").orderByAsc("id");List<User>list=userMapper.selectList(queryWrapper);list.forEach(System.out::println);}

3 组装删除条件

@Testpublicvoidtest03(){QueryWrapper<User>queryWrapper=newQueryWrapper<>();queryWrapper.isNull("email");intres=userMapper.delete(queryWrapper);System.out.println(res);}

4 组装修改条件

@Testpublicvoidtest04(){QueryWrapper<User>queryWrapper=newQueryWrapper<>();queryWrapper.gt("age",20).like("name","a").or().isNull("email");Useruser=newUser();user.setName("福新");user.setEmail("fx@xidian.com");intres=userMapper.update(user,queryWrapper);System.out.println(res);}

5 条件的优先级

lambda中的条件优先执行

@Testpublicvoidtest05(){QueryWrapper<User>queryWrapper=newQueryWrapper<>();queryWrapper.like("name","a").and(i->i.gt("age",19).or().isNull("email"));Useruser=newUser();user.setName("忠兴");user.setEmail("zx@xidian.com");intres=userMapper.update(user,queryWrapper);System.out.println(res);}

6 组装select子句

设置当前要查询的字段

@Testpublicvoidtest06(){QueryWrapper<User>queryWrapper=newQueryWrapper<>();queryWrapper.select("name","age","email");List<Map<String,Object>>maps=userMapper.selectMaps(queryWrapper);maps.forEach(System.out::println);}

7 组装子查询

@Testpublicvoidtest07(){QueryWrapper<User>queryWrapper=newQueryWrapper<>();queryWrapper.inSql("id","select id from user where id <= 100");List<User>list=userMapper.selectList(queryWrapper);list.forEach(System.out::println);}

UpdateWrapper

@Testpublicvoidtest08(){UpdateWrapper<User>updateWrapper=newUpdateWrapper<>();updateWrapper.like("name","a").and(i->i.gt("age",19).or().isNull("email"));updateWrapper.set("name","小黑").set("email","abc@xidian.com");intupdate=userMapper.update(null,updateWrapper);System.out.println(update);}