[英]OrientDB - Group by date query
我正在尝试在OrientDB中执行查询以获取每天的帖子数。 但是,我的GROUP BY查询失败,并且我看不到自己在做什么错。
我有一个数据库,里面满是3条帖子,所有帖子的日期都不同。
这是我的查询:
select
datePosted.format("dd-MM-yyyy") as day, count(*)
from
Post
group by
day
但是,它不起作用。 我希望它能够检索每天包含帖子数量的结构,但它仅能检索一个结果:
[#-2:1{count:3} v0]
有什么建议么?
我创建了这个结构,我认为这与您的结构类似:
create class Post
create property Post.datePosted date
insert into Post (datePosted) values ('2016-01-25')
insert into Post (datePosted) values ('2016-01-28')
insert into Post (datePosted) values ('2016-01-25')
insert into Post (datePosted) values ('2016-02-04')
这些是我检索所需结果的选项:
第一个查询 :
select day, count(*) as posts from (select datePosted.format('yyyy-MM-dd') as day from Post)
group by day
输出 :
----+------+----------+-----
# |@CLASS|day |posts
----+------+----------+-----
0 |null |2016-01-25|2
1 |null |2016-01-28|1
2 |null |2016-02-04|1
----+------+----------+-----
第二个查询 :
select datePosted.format('yyyy-MM-dd'), count(*) as posts from Post group by datePosted
输出 :
----+------+----------+-----
# |@CLASS|datePosted|posts
----+------+----------+-----
0 |null |2016-01-25|2
1 |null |2016-01-28|1
2 |null |2016-02-04|1
----+------+----------+-----
希望能帮助到你
EDITED
这是Java中的示例:
Java代码 :
private static String remote = "remote:localhost/";
public static void main(String[] args) {
String dbName = "DBname";
String path = remote + dbName;
OServerAdmin serverAdmin;
try {
serverAdmin = new OServerAdmin(path).connect("root", "root");
if (serverAdmin.existsDatabase()) { // if DB already exists
System.out.println("Database '" + dbName + "' already exists");
ODatabaseDocumentTx db = new ODatabaseDocumentTx(path);
db.open("root", "root");
Iterable<ODocument> results = db
.command(new OSQLSynchQuery<ODocument>(
"select day, count(*) as posts from (select datePosted.format('yyyy-MM-dd') as day from Post) group by day"))
.execute();
for (ODocument result : results) {
System.out.println("Day: " + result.field("day") + " Posts: " + result.field("posts"));
}
db.close();
}
else {
serverAdmin.createDatabase(dbName, "document", "plocal");
System.out.println("Database " + dbName + " created");
}
serverAdmin.close();
} catch (IOException e) {
e.printStackTrace();
}
}
输出 :
Day: 2016-01-25 Posts: 2
Day: 2016-01-28 Posts: 1
Day: 2016-02-04 Posts: 1
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