2020-03-05

#mybatis_plus 常用

1.通过已有buildingId 去中间表buildingMid取对应的buildingBasicId的集合

用到一个selectList（QueryWrapper<>）
buildingMidMapper.selectList(new QueryWrapper<BuildingMid>().eq("building_id",VO.getBuildingId()))

.stream()                              ===>以上为select语句中的查询条件  select * from buildingMid where building_id=#{buildingId}

.map(BuildingMid::getBuildingBasicId)           

.collect(Collectors.toList());             ==>      将buildingMid 中 get的buildingBasicId放入List集合中   做为select查询目标返回

2.通过分期id查分期下已经做过映射的楼栋集合，用分期id查楼栋buildingIdList 再用buildingIdList去中间表buildingMid查询做过对应关系的楼栋 。

buildingMidMapper.selectList(new queryWrapper<BuildingMid>()

.lambda()

.in(BuildingMid::getBuildingId,buildingIdList))

.stream()

.map(buildingMid::getBuildingId)

.collect(Collector.toList());