mongodb查询

tag_cid存储结构：

{"cid":"12313213","tags":["java","IT男"，"江苏南京","单身狗","宅男","python"]}

  -- 查询数组中包含某个元素 

db.tag_cid.find("tags":"java")

  --查询数组元素中包含多个指定值的文档，全部包含，顺序无关

db.tag_cid.find({"tags":{"$all":["java","宅男"]}})

db.tag_cid.find({"tags":{"$all":["java","宅男"]}}).count() 

-- 查询返回指定字段 

db.tag_cid.find({"tags":{"$all":["java","宅男"]}},{"cid":1,"_id":0})

  -- 批量查询遍历 

db.tag_cid.find({"tags":{"$all":["java","宅男"]}},{"cid":1,"_id":0}).forEach(function(x){print(x.cid)})