Question

我有一个具有以下表格的SQlite图像数据库：

CREATE TABLE crowd_labels (mid int, attribute text, label text, primary key (mid, attribute));

CREATE TABLE modules (
    mid int primary key,
    project_id int,
    src text
, mature_content, license);

CREATE TABLE scores (mid int,content_bicycle real, content_cat real, content_tree real, emotion_scary real, media_oilpaint real, content_bird real, content_dog real, emotion_gloomy real, media_3d_graphics real, media_pen_ink real, content_building real, content_flower real, emotion_happy real, media_comic real, media_vectorart real, content_cars real, content_people real, emotion_peaceful real, media_graphite real, media_watercolor real);

我可以分别执行以下查询，但是我想知道如何将它们组合为一个查询：

sqlite3 mydatabase.sqlite <<EOF  > cat_pictures.htm
    select "<img src=""" || src || """ height=200>"
    from modules, crowd_labels where modules.mid = crowd_labels.mid
    and attribute = "content_cat"
    and label="positive"
    limit 100;
EOF

sqlite3 mydatabase.sqlite <<EOF  > watercolor_pictures.htm
    select "<img src=""" || src || """ height=200>"
    from modules, scores where modules.mid = scores.mid
    order by media_watercolor desc limit 0,100;
EOF

第一个查询将通过检查“ crowd_labels”表返回一个包含100张猫图像的html文件，第二个查询将通过检查“得分”表返回一个包含100张水彩图像的html文件。

但是如果我想将两者结合起来，也就是给我既是猫又是水彩的图像的交集，我该怎么做？

很抱歉，如果这是一个非常简单的问题，但是我对SQL的背景经验为0。

Answer 1

只需联接所有三个表：

SELECT '<img src="' || src || '" height=200>'
FROM modules
JOIN crowd_labels USING (mid)
JOIN scores       USING (mid)
WHERE attribute = 'content_cat'
  AND label     = 'positive'
ORDER BY media_watercolor DESC
LIMIT 100;

如何从SQLite3中的多个表查询图像

1 个答案: