Question

我有以下MySQL查询加入另外两个表..

SELECT  plants.plant_id,
        plants.scientific_name,
        plants_features.features,
        plants_features.features_id

FROM    plants_features,
        plants2features,
        plants

WHERE   plants_features.features_id = plants2features.features_id

AND     plants2features.plant_id = plants.plant_id

我很满意输出。

plant_id,scientific_name,features,features_id
3,"Actaea matsumurae 'White Pearl' (Bugbane)","colourful fruit",6
11,"Heuchera 'Beauty Colour' (Coral bells)","salt resistant/coastal",15
18,"Phyllostachys nigra (Black bamboo)","colourful bark",5
26,"Carex morrowii 'Silver Sceptre' (Japanese sedge)","drought tolerant",18
27,"Heuchera 'Obsidian' (Coral bells)","salt resistant/coastal",15
29,"Dianella tasmanica 'Tas Red' (Flax lily)","drought tolerant",18
38,"Stipa tenuissima (Mexican feather grass)","attractive seed-heads",2
38,"Stipa tenuissima (Mexican feather grass)","invasive/self seed/suckering",13

您可以从plant_id＆＃39; 38＆＃39; （底部两行）它每条记录输出多行。

我的问题是伙计们，你能否告诉你新的MySQL查询究竟需要什么来确保一行记录中的多行是＆＃39; plant_id＆＃39;？

提前致谢，理查德。

Answer 1

您需要分组和aggregation functions。您可以使用GROUP_CONCAT获取以逗号分隔的列表：

SELECT  plants.plant_id,
        plants.scientific_name,
        GROUP_CONCAT(plants_features.features) AS features,
        GROUP_CONCAT(plants_features.features_id) AS feature_ids
FROM plants_features
JOIN plants2features
  ON plants_features.features_id = plants2features.features_id
JOIN plants
  ON plants2features.plant_id = plants.plant_id
GROUP BY plants.plant_id, plants.scientific_name;

还使用JOIN语法而不是逗号和where。

MySQL＆＃39;多行＆＃39;从两个加入挑战

1 个答案: