MP的双表合并查询

1、双表合并查询

/*两表合并*/
public void te() {

    /*全选*/
    List<ModelEntity> modelEntities = modelDao.selectList(null);
    List<ModelControlVo> modelControlVos = new ArrayList<>();

    /*将查询得到的数据赋值给modelControlVos*/
    modelControlVos = modelEntities.stream().map(modelEntity -> {
        ModelControlVo modelControlVo = new ModelControlVo();
        modelControlVo.setModelId(modelEntity.getModelId());
        modelControlVo.setModelName(modelEntity.getModelName());
        modelControlVo.setModelType(modelEntity.getModelType());
        return modelControlVo;

    }).collect(Collectors.toList());

    /*获得所有的modelId并去重*/
    Set<String> modelIdSet = modelEntities.stream().map(modelEntity -> {
        return modelEntity.getModelId();
    }).collect(toSet());
    /*判断取出来的模型表有数据*/
    if (modelIdSet.size() > 0) {
        /*条件查询得到分数表的数据*/
        LambdaQueryWrapper<JssChainModelScore> wrapper = Wrappers.lambdaQuery();
        wrapper.in(JssChainModelScore::getModelId, modelIdSet);

        /*如果只要某一个属性，可以select*/
        /*wrapper.in(JssChainModelScore::getModelId, modelIdSet).select(JssChainModelScore::getModelId);*/
        List<JssChainModelScore> jssChainModelScores = jssChainModelScoreDao.selectList(wrapper);

        /*取出它的模型名和它本身作为map*/
        Map<String, JssChainModelScore> jssChainModelScoreMap = jssChainModelScores.stream().collect(Collectors.toMap(JssChainModelScore::getModelId, p -> p));

        /*遍历赋值*/
        for (ModelControlVo modelControlVo : modelControlVos) {
            JssChainModelScore jssChainModelScore = jssChainModelScoreMap.get(modelControlVo.getModelId());
            if (jssChainModelScore!=null){
                modelControlVo.setSynthesisAVGScore(jssChainModelScore.getSynthesisScore());
            }
        }
    }

2、双表合并查询-分页
在查询合并后，加入分页

    int pageSize = 2;
    int pageNo=3;
    int total = modelControlVos.size();
    int pafeSum = (total+pageSize-1)/pageSize;
    List<ModelControlVo> subList = modelControlVos.stream().skip((pageNo-1)*pageSize).limit(pageSize).collect(Collectors.toList());

3、一对一查询合并

/*单表合并*/
@Test
public void getOneMerge(){
    int Id = 1;
    LambdaQueryWrapper<CollectEntity> wrapper = Wrappers.lambdaQuery();
    wrapper.eq(CollectEntity::getId,Id);

    // 先查询用户信息
    CollectEntity collectEntity = collectDao.selectOne(wrapper);
    
    DetailEntity detailEntity = new DetailEntity();
    detailEntity.setCollectId(collectEntity.getId());
    System.out.println(detailEntity.toString());

}